It's their choice to get it or not. If you get it and complain that the characters you pay for is too expensive, then you just proved how much of a sheep you are. If you did not get it, and say "Eh, I don't -need- those characters" then power to you. But at the end of the day, people have the choice to not get Jill or Shuma. (There's a thread for this talk.) Just because there's DLC doesn't mean the game is incomplete. In fact, unless you were on the game development -project- for said game, I just think most people who say it are kinda blowing smoke out of their ass. Soooo no one is holding a gun to anyone elses head and saying "BUY SHUMA OR I'LL BLOW YOUR [tornado fang]ing HEAD OFF!"
But on the topic of Sentinel, I think it gives him more of a balance, look at Phoenix. Over powered and broken like hell, but she has low health to balance that out. How is it okay to have Sentinel--who has armor frames, supers that can be chained easily from OTG moves, and distance spamming with anything -more- then 900,000? If that's not right then Ironman should have armor frames where he is invincible, (Tony's armor is more durable and tougher then any Sentinel) Thor should have it too, as should Captian America's shield -not- lose momentum when he's hit. Honestly, I think it's either that or Sentinel loses the armor frames and the quick speed of his mouth lazers. The move is about making the game more fair and balanced and no one should have to look up videos--ONLINE just to learn how to beat -one- character and base their teams off of beating that one character.
Edit: I think that we're way past the point of saying the game is a bit early for fixing, namely for the fact that I've run across people who've had 3,000+ matches already. But besides that, should they wait a year to fix some problems? Or maybe three years? Or ten when Marvel vs Capcom 4 comes out? (Hehehe....team "Ten more years") It's never "Too early" to fix problems in general. Why wait later? For -everyone- to look online, base their teams on beating one guy, everyone stops using Sentinel and then---they release a patch that makes him weaker? That makes no sense.