I don't think it's overreacting. On my part I was just saying "IF" it turns out like that I'll be less inclined to buy it. It's all personal taste, not everyone wants to go with the flow if a series completely changes it's mechanics. I even said that I'm giving Capcom the benefit of the doubt and think it'll still be MVC and not just TVC reskinned.
However you have to realize that while you like TVC, not everyone feels the same. Gameplay is pretty much everything in a fighting game to me. Even if I like the characters, if the gameplay isn't satisfying to me, it's just not worth a purchase to me. I mean I loved Uncharted 1, and then 2 changed the forumla a bit but it was improvements, and 2 became my favorite game this gen so far. Yet if Uncharted 3 became a pure Tomb Raider clone, I wouldn't buy it purely because Drake's in it. Same here, if MVC stops being MVC, then I'm not going to buy it purely because it has Marvel and Capcom characters in it. The same way I stopped playing Mortal Kombat after 3 because it just stopped being MK to me.
But, with that said, like said above, I doubt it'll lose that MVC feeling. I'm sure it'll be a great game. I just, like I said, agree with Tim that I'm not into a complete overhaul to dumb down the system or make it TVC 2.