SF4 is accessible at a basic casual level (ignoring Ultras/Focuses/Specials) that plays like an updated non-Turbo SF2. The issue comes once you start trying to access the newer mechanics - the FAs the double-motion Ultras, and the FADCs, Learning the game quickly escalates to a point where it requires both time investment and reflexes that may not be available in the player. They're aware of the issues here, and its why SFxT experimented with having chains and explicitly didn't use double-motion Supers.
They implemented RFCs in part for their effect on lower-level play, allowing players to more easily hit their Ultras, since the hit-stop and crumple gives far more time and requires far less execution than the FADC Ultra that even the pros drop semi-regularly (the EG Special.)
The control scheme for FGs is a massive hurdle for people- modern games don't play like them. I have a buddy who played MK back in the arcades years back, and when introduced to MvC3, was flummoxed at the QCF/DP motions because he hadn't seen them before. The control scheme in and of itself is a real barrier to entry all on its own, and even if you're not aware of that, Capcom definitely is. There's a reason MvC3/BB have a beginner mode. Why MvC3 has a magic series. Why P4A has auto-combos. Why SFxT has chains. They're trying to get as much of the fun stuff as accessible as possible to as many people as possible without breaking the game. And it's actively hard to do, and I don't envy their position.
You may not think this is important - but it really is. Casual non-competitive players make up the vast majority of sales, and sales are what provide the funds for future game development. The more the games are accessible to a casual audience, the higher the sales potential, which helps grow the business/scene. Yes, it's basically impossible for the games to hit LoL-tier because of the "run on a toaster" thing. That's perfectly fine. But it doesn't mean that you just "develop for the hardcore" and make the games only for your hardcore, because that's the path to a slow, inbred, death.
