Now you're getting it.
Dumbing down gameplay mechanics isn't going to drastically change how a game sells. The masses see things more superficially than that. Which is why MK and tons of other games sell on the power of "sick graphics, bro."
Well drastic or not, if a company perceives doing something a certain way is going to make the game sell more, from a company's perspective, they are within their right to do so.
also, despite MVC3's low barrier of entry, it still had a high skill ceiling. 90% of the people complaining here cant perform the way the top 20 in the tournament scene do. So your really just complaining about something you'll never attain anyway. There is no reason this game cant have a higher skill ceiling than mvc3. TVC was considered a better game, and this game seems to lean more in that direction.
End of the day, what do you, or should you care, if casuals have a better time entering and enjoying the game, if the skill ceiling is going to remain high?
End of the day, the tournament scene still gets a game that requires a lot of skill to master for tournament purposes.
The new tag mechanic wont be so bad because you can come in and do ANY MOVE. So in some ways thats better than 3 predetermined assist moves. The only thing it might hurt or are for OTG stuff, but that itself was a bit excessive and required less skill in MVC3.
End of the day. Low barrier of entry doesnt equal low skill ceiling.