I can't see any real reason that "getting rid" of any one member of the Federation would have such a significant impact on the whole Starfleet or on all the other federated planets. Of course it would be a tragedy, but why would it break up the Federation or affect the fleet?
Well it seems that the enemies of the Federation as portrayed on-screen disagree with you, ESPECIALLY the Borg, who seem to have headed straight for Earth in each attach, barring attacking a few outer colonies.
For whatever reason Earth is considered the centre of the Federation, politcally, strategically and symbollically.
Presumably because it's the capital planet and central control hub for Starfleet.
But
JNG makes a valid point when he notes that the loss of Earth, by itself, would not necessarily lead to the fall of the Federation. However, the assimilation of Earth would give the Borg a territorial foothold from which to continue their invasion of the quadrant.
If the Borg had sent two cubes, as opposed to one, during "First Contact," they would've assimilated Earth the conventional way. Ten would've made it even easier.
No, it wouldn't - you are assuming a lot of things that re not shown on screen, starting with...
No, it's shown onscreen, and quite plainly so.
Admiral Hayes was assembling everything they had - they weren't sending "just enough to beat the one cube."
You think? You really think it was desperate enough they sent everything they had but they left one of their most powerful units sitting around on the Romulan border for largely spurious reasons?
I think it far more likely they redeployed a large force to meet the threat on favourable terms but still had assets to cover and areas to protect. We know, for example, that Klingon space is relatively close to Earth, but given the bad relations at the time do you think Starfleet stripped their defenses bare?
Whilst it's probably fair to say that Starfleet didn't re-deploy EVERY ship it had, it almost certainly re-deployed every ship it could coneceivably spare. Remember, they were engaging an enemy whose single ship had destroyed forty of theirs six years before and whom they only defeated with a fluke of luck. (What would have happened if the Borg had had a better firewall in 2367?)
Further, the Borg cube was first engaged in the Typhon Sector at the edge of Federation space. That means that Starfleet fought a running battle with the cube that dragged across the Federation -- and it didn't end until the cube had reached Earth orbit. And there were only a few ships left, and more and more were getting picked off even in the only few minutes of the battle we saw onscreen. Starfleet was very clearly losing until Picard realized that if they fired at the magic Achilles Heel, the cube would go 'splodey.
And the only reason the cube lost was because Picard showed up and coordinated large doses of firepower against the cube's weak spot.
I would say Picard showing up certainly helped - but the Cube had already suffered massive damage, maybe the continued attack would have destroyed the cube anyway. Picard's knowledge merely made things simpler.
Nonsense. What the movie again. The cube was winning and barely damaged before Picard showed up, and it was still picking off ships very easily whilst the Federation ships were barely scratching it.
Had they sent two cubes, Starfleet would have lost and Earth would have been assimilated.
Really, we're putting a lot of faith in the word of the enemy if we think that the Borg wanted to assimilate Earth or defeat the Federation in these various encounters.
The true motivations of the Borg remain unclear - but VOY shows that the Borg are interested in a great variety of things, ranging from sampling a newly encountered cuture, to assimilating some resources, to assimilating a species, to terminating a species. Their interests even include deliberately attacking the victim piecemeal, to prompt the development of ever-better defensive strategies and technologies, as in VOY "Child's Play".
Quite possibly, the two Cubes sent to Earth both had a mission other than the assimilation of the population, or termination of resistance.
Like sbk1234 sez, "In-universe answer, the Borg don't actually learn anything from experience. They assimilate to aquire more knowledge." So it wouldn't do to terminate a species, not before the Borg have learned all they can from that species.
Timo Saloniemi
Interesting point. It's entirely possible that the Collective's goals were met either way. If they assimilate the Federation, great, and if they don't, then that prompts technological development that will make them a tastier target later on.
At least one novel,
DS9: Lesser Evil by Robert Simpson, noted that some Federation strategists postulated that the Borg may have been testing the Federation, seeking to measure its ingenuity, rather than seeking to dedicate its full resources to the assimilation of the UFP.
Well, the first time around, Adm. Hanson seemed pretty confident he had the Borg's number, and it was forty starships.
After he was proven wrong, I'm sure somebody at SF Command came up with another number. And he or she seemed to get it more or less right: the Cube didn't get through in ST:FC. Had it reached Earth orbit, it couldn't have done the classic scoop-the-cities trick, not with a hundred ships breathing down its cybernetic-collective neck (and well into the process of breaking said neck).
Um, it
did reach Earth orbit. And there were maybe, maybe 20 ships still battling the cube when the
Enterprise showed up -- and the thing was winning, picking them off one at a time whilst receiving minimal damage itself.
And even its ability to deploy weapons of mass destruction was doubtful at that point.
Hardly. A ship's phasers were established to be capable of exterminating all life on a planet's surface as long ago as TOS's "A Taste of Armageddon," and Borg weapons were always established to be far more powerful than phasers. The cube's ability to deploy weapons of mass destruction is not the least bit in question.
In First Contact however, it was the Borg.
No more feared or formidable than Nazi Germany - we are talking the force that had just conquered the whole of Western Europe in about three months seemingly effortlessly - seems pretty Borg-like to me.
Nazi Germany didn't possess technology
centuries more advanced than anything Great Britain did.
Really, a more comparable battle would be World War II-era Great Britain vs. the Aztec.
Given the short range at which combat seems to take place (one must assume at longer ranges the weapons are ineffective or something) no more than a couple fo dozen ships can engae at any one time.
Um, no. We've
seen hundreds of ships do battle during the Dominion War at once.
BTW, for anyone who wants to see just how truly one-sided a full-scale war against the Borg Collective would be in conventional military terms, I'd suggest reading David Mack's excellent
Destiny trilogy -- which is far better and has far more depth than its summary, "The Borg Collective decides to exterminate the Federation with a massive invasion force," would suggest
(Hey, I didn't write it.) Probably Earth and any Federation planet are not prize targets for them; they were tricked into thinking Enterprise-D had capabilities beyond their understanding when it disappeared on them at the end of "Q Who?" because they didn't know Q did it. There may also be a unique or unusual understanding of or curiosity about the Federation as a result of the Hugh experience in "I, Borg" and other stuff, but it's clear it has somehow led the Borg to be playing games. I see no reason they'd treat anything in the Federation as some huge deal they had to rush across the galaxy to deal with anyway; as Guinan said, the Federation is just raw material to them at this point, and probably only the Queen's whims, the intel from recaptured Picard and Seven of Nine, and several healthy doses of luck have kept that raw material from being consumed. 
