But their entire plan...
And what do you think their plan was?
From what I can remember, it was to go back in time, stop first contact, and assimilate Earth in the 21st Century. Lots of people have been explaining why this doesn't make sense for years, but I'll say it again now. Ever since the first time we saw the Borg we learned that they were primarily interested in acquiring new technology. So in their first attempt to assimilate Earth and the Federation they sent one ship. It got blown up when the Enterprise crew found their Achilles heel. So years later, in First Contact
, the Borg sent another lone ship to Earth, it got blown up. But it launched a Sphere that went back in time to a few days before first contact.
Now here are the things that don't make sense:
First, If the Borg have the ability to travel back in time why didn't they do that when they where still in the Delta Quadrant? Then travel unopposed to 21st century Earth and assimilate it.
Secondly, why would the Borg even be interested in assimilating 21st century Earth? They don't have any of the cool 24th Century technology that the Borg were originally interested in. Assuming they did assimilate Earth back in the 21st Century all they would have is one small insignificant planet thousands of light years from their base of power.
Thirdly, why would the Borg even think to stop First Contact? That indicated a degree of lateral thinking that the Borg were never shown to posses. They see someone with some piece of tech they want, so they take it. Nothing more complex than that. The Borg were remarkably single minded. That was part of their appeal. They were more of a force of nature than an evil race. They were kind of like the shark from Jaws
, they roamed the Galaxy consuming what they wanted. Nothing more.
Fourthly, whatever happened to the adaptive Borg we saw on TNG? The ones who would adapt to any weapons frequency or tactic that is used against them? The first time the Enterprise crew fought the Borg it took an act of Q to save them. The second time Data jacked into their Unimatrix and put them into Sleep mode. Presumably they fixed their Network settings to prevent that from happing again. All the while Starfleet Officers were free to walk around Borg Ships as long as they didn't pose a threat. In First Contact
the Borg could still adapt to weapons frequencies after they took a few hits. But they seemed to forget to adapt to any of Starfleet’s tactics. So even after showing how much of a threat that Starfleet Officers could be when they were poking around. The Borg still let Picard’s tactical teams get all the way to main Engineering, just because they kept their weapons down and didn't present them selves as an immediate threat.
I could go on, but like I said all of these points have been brought up by others over the years.
There are some plausible explanations.
Why didn't they go back in time in the Delta quadrant? Perhaps because the transwarp network didn't stretch as far back then, and they couldn't easily get to earth. Even though assimilating Earth wasn't the primary mission objective, it was a secondary one.
Why would the Borg be interested in assimilating Earth? Well, the Borg Queen, unlike the drones, is an emotional being. And she's had two big embarrasments. First of all, she had the Enterprise snatched away from her in Q Who. Secondly, the defeat in BoBW. The Queen would want revenge. Besides, once she received the message the drones in Regeneration sent, it would undoubtedly contain the whole story of how they were trying to assimilate the Earth. Since that message did indeed reach the Collective and the primary mission objective was completed, the Queen chose not to mess with a sequence which was guaranteed to produce the desired outcome.
Why did they try to stop first contact? Well, the way I see it, that was only a secondary goal, not the primary goal.
The primary goal of the Borg in First Contact was to send the Collective in the 21st century information about the future.
Look at what happened. The Borg Sphere tried to destroy the Phoenix, but that was quickly stopped. What did the Borg do then to stop first contact? Pretty much nothing. Instead, the Borg concentrated on fixing the deflector to be the whatever so they could contact the Borg of the 21st century.
But why would they want to do that? To get reinforcements? Why would they need that? After all, humanity's in ruins, they won't be able to mount much of a resistance. And each Human you assimilate would add to your numbers making your job so much more easier. No, the Borg didn't need reinforcements. But to send the 21st century Borg information about the 24th century, that would be very valuable. And THAT is the primary mission - and that is what we see them doing. The queen concentrates on this to the exclusion of all else, and it is only once this objective is out of reach - when the deflector is destroyed that she says, "There's been a change of plan." And only then does she try to stop the Phoenix again.
So stopping the phoenix is a secondary goal. Assimilating Earth is just a secondary goal. It's sending information about the future to the drones of the past that the Queen was most interested in. And we even see that the drones recovered in Regeneration went back to doing precisely this! They once again attempted to complete the primary mission from FC - to send information about the future to the drones of the past!
As for your fourth point, let's not forget that the Borg were concentrating mostly on assimilating the Enterprise, not fighting crewmembers. And they did assimilate some. But they were concentrating on their primary mission.
...and adding the Borg Queen were terrible.
Why shouldn't the Borg have an embodiment of the Collective mind?
After all, if you have billions of drones connected together, why shouldn't they function as one mind? Your brain cells do it easily enough. And why shouldn't the Queen be an individual, emoting all over the place? Your brain cells don't have any individuality and can't emote, but when they all act as one, they form your mind, don't they? A mind with a sense of individuality and emotions. So why should it be so implausible that the Borg do exactly the same thing?
If the Borg Queen had only been an embodiment of the collective, kind of like Locutus, that wouldn’t have been so bad. Instead it was clear in First Contact, and Voyager later on, that she was the leader of the collective. That is a big difference. The problem with the Queen, was that the Borg were shown to not have a single leader. They were all of one mind. It was explicitly stated in Q Who what the advantages of having no single leader were. Troi said that a single leader can make mistakes, but the combined whole is less likely to. In First Contact and afterwards The Borg Queen was always making mistakes. The Borg were much scarier and a more effective villain before the Queen. Before, you couldn't out run, out fight, or even out think the Borg. After, it was pretty easy to out think or trick the Borg Queen.
The Borg Queen was just lazy writing. They could have kept what was unique to the Borg, not having a single leader, and had a really cool villain in the Borg collective. But they needed a bad guy for Picard to go Mano a Mano with (again), at the climax of the movie.
lol, you are proving my point! You yourself admit that I am right when you claim, "The problem with the Queen, was that the Borg were shown to not have a single leader. They were all of one mind."
That's exactly right, they are one mind - and that Mind is the Queen. The queen is no more a leader of the Borg than your mind is the leader of your brain cells.