That's my point Jason, the entire purpose of a reboot is to remake everything from scratch even if they use familiar or even duplicate events/details. What this means is that the reboot wouldn't affect TOS alone, it would affect the entire ST timeline into a new alternate canon. In ST terms maybe parallel universe might work as best explanation.
In other words TMP might play out differently in this timeline as would the Lost Era, TNG and the rest. It's a brand new continuity and that's what I like about it because it opens the possibility of doing things differently and not have to run into the problem of "but that goes against what this other series said first". The problem with Enterprise, amongst other things, was that they tried to fit it into the old canon and changed so much of what just about every other series had implemented that ultimately it failed in most aspects, many of these were also broken between themselves to begin with so all ENT did was enlarge the convoluted mess to the point where just about nothing made sense.
I'd like to think that Braga changed BSG for artistic and creative purposes, not to attract newer/younger crowds (Though the goal of any show is to garner ratings), but as a writer that is how I tend to look at things. Nevertheless I think any reboot has the potential for working if done right, BSG certainly doesn't have exclusivity here.
As to the age of the actors, Starfleet Academy is like college right? Well they just graduated from Starfleet Academy which would make these characters about what 22 (Average age of graduating college after a 5 year degree if graduating high school at 17 which is average age of graduation there)? Most of these actors are mid-20s to late-20s possibly making them actually too old for the characters.
Also Trek has been stagnant for me for a long, long time; which isn't to say that I didn't enjoy the different series, I did, but the old canon is too condensed and filled with too many inconsistensies already. A totally new timeline and new approach peaks for me an interest in Trek again where yet another time-travelling continuity breaking story would fizzle for me on the spot. (Well at least they didn't put in any Nazis on this one sheesh).
In terms of what Gene Roddenberry would think/want, I think it's important to pay tribute to and maintain the spirit of what he created but not necessarily continue his exact work exclusively. Just because a filmmaker has a different style or decides to tell the same story in a different manner doesn't mean it is disrespectful to the original creator. This is not to say I don't understand your feelings towards wanting things to stay the same or keep in line with what was already established (I have this exact feeling with that horrible new Terminator movie in the works which rips apart all things Cameron) but for one reason or another I feel this has the potential to make things new again instead of continue a formula that for me and some others who have sat through every series and movie feel it's time for a change and something new.
On the ship don't get me wrong, I wish this movie used a sleeker Connie refit (If not the proper Connie reift herself) and we had the burgundy uniforms and all good things ST2. Meyers managed to reinvent Trek and keep continuity going but Trek then was still quite limited (Only TOS, the toons and the motion picture). JJ has to work against Ent-TOS-Toons-TMP-TNG-DS9-Voy all that convoluted broken continuity, all that established background and all those stories hashed and rehashed over and over. If he's not making something completely new (Post Voy) and is tackling established characters in a very established timeline, I think it is more respectful to Roddenberry and the fans to retell things from scratch as opposed to changing yet again what the originals stated as a poor replacement. If this is supposed to be the original canon, then I would be sorely disappointed in this film believe me.
Besides the old Trek is still there; don't think of this as a replacement for the original think of it as a possible alternate version companion of the way the same story might have been told. That's how I'll see it and I'll judge this movie based on its own strength and weaknesses not only in contrast to what was made or established before.
Still trust me I understand your concerns and this might turn out badly in the end but my hopes are up