I'mma be honest.
The lack of marketing was a big issue here, brehs. My little brother (who only plays 3 games on his Xbone: NBA 2K, Gears and MAAAHVEL) didn't know the game even launched until Sunday. He bought the game but that's not the point. If they're failing to effectively reach and inform people who love the series (and are going to be their most reachable customers) but don't keep up on video game news (he doesn't go to gaming forums or seek out gaming news)...well, this is how you end up here.
And as we all know, the lack of X-Men hurts. His first questions when he loaded up the game were, "where is Akuma?" and "where is Wesker"?
As pointed out, the game is also much more difficult than MvC3 was. The change to the launcher and having to push d.HP and HK sending people to the ground instead of the special button is a massive change that continues bedevil both of us for now and the foreseeable future has soured his early experience of the game. 4 years of muscle memory takes more time for many of us than others. Whether he sticks with it or not is anyone's guess. Instead of him being a sales and hype generator among his group of friends, he will likely have no influence at all.
That said, the right DLC characters can fix most of the issues. Along with a lower price point.