Sure there are. The biggest being that Anakin is an incredibly unsympathetic character. From the moment Hayden Christensen walks onto the scene, you could see him falling to the dark side and no one cared.
Absolutely. How much more satisfying would it be to have seen a nice guy go bad... than it was to have a petulant rebellious teen stay petulant and rebellious?
It's clear we're supposed to associate the innocent kid from the first movie with the teenager from the second and third ones, but this is problematic in itself. There's a natural disconnect, almost as if they're two completely different characters (not helped by everybody else still being played by the same actors - what, does being a Jedi make someone enter puberty quicker?).
Which is true, Anakin's fall would have been much more dramatic had he been older, wiser and gentler, but that has nothing to do with the point I was making.
While I do empathize with your broader point that to some degree ST2009 didn't necessarily need
to be a reboot -- there was definitely mileage in it perhaps bridging the eras of ENT and TOS in the canon, and certainly if there is a starship crew in Star Trek whose pasts are still very much an open book then its the TOS crew, who never actually had a proper introduction story -- the reality
is that the word "prequel" holds certain connotations with the general audience that Paramount hoped to target. They wanted to make a Star Trek that would appeal to as broad a cross-section of the audience as possible, and a prequel story still gives off the impression that it's being made for the fanbase first and foremost. Like it or not, that isn't the market that ST2009 and STID were targetting.
That little word, "reboot", makes all the difference in marketing this
Star Trek as being a fresh take on the concept. Where a "prequel" to Star Trek might have been offputting to an audience who don't feel they're up to speed on the canon, a "reboot" opens up the possibility that this movie is an 'entry level experience' that anyone and their dog can enjoy, irrespective of whether they've ever seen Star Trek before or not. As silly as it sounds, whether the 2009 movie was being marketed as a "prequel" or a "reboot" really could have made a big difference between someone choosing to buy a ticket to see it or not.
See, the trouble with using the Star Wars prequels as a litmus test for the ability of a prequel to reach a wide audience is that Star Wars has got (and always HAS had) a much broader market appeal than Star Trek. Star Wars doesn't (or didn't in 1999 at any rate) have the perception of being as tied up inside its own canon as Star Trek is. In constrast, Star Trek still had the perception of being 'that show which is made for Trekkies', which is why this being a "reboot" was so important. They needed to assure the general audience that this was a Star Trek for everyone
From a marketing perspective, let alone from the perspective of rebuilding a Star Trek brand that was in complete tatters following a string of percieved flops, this being a brash new reboot of the franchise was absolutely crucial
to making the 2009 movie a success.