Have you seen the kind of stuff in Blaz Blue? Pretty certain it'd make for an insane Marvel. And while 8 way airdash is fun its not really helpful to developers who want to make a balanced game. It leads to a LOT of Touch of Death, loop, and infinite scenarios that are unfair to the rest of the cast. Its a bitch balancing such fighters who are meant to use it without creating another scenario like MVC2 where folks wont really be viable without having at least some of team 10 more years on deck.
I've seen and played BlazBlue and I can tell you, it's no Marvel.
As for 8 way airdash (and other things), that kind of free mobility is one of the things that's helped defined how Marvel plays. No other franchise has given players the same freedom of movement. On a related note, it's the freedom that always attracted the players to the Marvel games. Just look at the series' history, it's the games like XvSF, MvC2, that offer alot of freedom (and brokenness) that are highly loved and respected, and those like MvSF that tried to control this that are hated.
And regarding team selection, people forget that for all its "imbalance" with only 16 viable characters, Marvel 2 has arguably the most number of valid playstyles of any fighting game ever. Rushdown, TOD, Zoning, Lockdown/trap, runaway, etc. are all viable in the game due to the heavy team dynamic. Just because MSP and Matrix/Wong both have Storm doesn't mean they'll play the same. No, one is a pure rushdown team (MSP), while the other is a zoning/keepaway team.