That may be the case, but from the outside looking in, every SF game looks and feels exactly the same. Same moves, same animation of attacks, same thing over and over again with a few small things added and a few new characters. I use this as an example for gamers looking at DMC if Capcom had made a DMC5 instead of DmC; it would've been treated like "same old DMC game" and critics would speak o fit as such. However DmC was a big change and created so much attention that it made the series the talk of the game community again.
Yeah it was the talk of the community for BAD reasons and those interactions among the community are what made DmC to sell poorly to begin with.
DmC is one strong evidence that making alterations for the sake of drawing in publicity won't end up good especially when the publicity is bad to begin with.
With the spread of internet and opinions and people giving input ****ing off your fanbase by making changes they either don't like or view as good/necessary is the last thing you want to do if you want to make sales.
Also, wouldn't a DmC2 just be what DMC4 was to DMC3. An improved/altered DmC.
When you find something that works and everyone love it you try to improve upon it and evolve it to make it better.
SF example is a bad example because SF is a fighting game. Fighting game's have an establish system and if you try t0 radically change it or make it something else you either create a fighting system that the fans of the series don't like or is absolutely broken or a shadow of the original.
Tekken is the highest selling fighting game (or action game) of all time but it still uses the same combat system it had for the first game. The same characters who uses the same moves and attack animations and the only difference is the fact they clean up the animations, update the models, throw in some new mechanics, and have spin-off games with new mechanics like the Tag series. Its fundamentally the same game.
SCV tried to drastically alter its combat system by doing a lot of things and one of them being the addition of Super Moves like in Street Fighter or 2D fighters and removed a lot of characters/play-styles that people loved (Talim) and other alterations as an attempt to streamline the mechanics. It was very different from the last 4 games and it was radically hated and herald as the worst in the series (it does have the best character creator/customization mechanics).
That is just how sequels work especially in action/fighting games.
If you want to play a different game that is what other series are for.