Well out of all that up there I did manage to see the point of the final paragraph, and I do agree that one of the most interesting things they could do is implement character specific mobility options that support characters weaknesses and are unique to them.
I am all in favor of some characters being more mobile than others. Characters that are not mobile usually tend to be slow overall, and I think that slow characters should be embraced for the style that they are supposed to represent instead of being abandoned due to the fact that "slow isn't as competitively viable as fast". There are other ways to make "slow" characters fun and effective.
For all its virtues, this is the thing that I
don't like about Project M. They just increased Melee's game speed, thinking "Melee was a fast game, and Melee was a good game, so let's make Project M faster than Melee, which will in turn make Project M better than Melee". It wasn't a horrible move by any means. I mean, I know there are tons of people who just wanted a faster Smash however they could get it. But increasing the overall game speed was definitely not the ideal move, or the only way you can make a game seem "faster". This is especially true if you start to consider pacing as an entertainment factor, i.e. having "Brawl" moments of speed and "Melee" moments of speed in the same game.
Take a look at Ike for example. I feel like the mindset for his Project M changes was "Ike is a slow character, which means that he needs mobility, so lets allow him to cancel his side-B" because high mobility has become such a standard for viability in Melee. Simply giving the positive assets of a viable character to another character who isn't as viable is not always the best design choice. Yes, the changes to Ike's side B made him more viable. Yes, Ike is by no means a clone of another mobile character. But still, I think Ike could have benefited greatly from another mechanic that would have synergy with his role as a heavy sword character.
I hope I've made my point clear enough. Admittedly, I haven't thought about every little aspect of the point I'm trying to make, but I think I can TLDR it for you:
Having fast and slow characters is good because diversity is good in the long run(not to say that a game can't be all speed and still survive for years). So, I am more in favor of giving characters unique and thematic mechanics as opposed to universal mobility options.