I wouldn't call this,
'expertly tuned'. I'd call it stupidly overcomplicated.
Well then you would be wrong. I mean that isn't even the complicated part of SF4 for one that's just a button input for a special move. It's not FADC or anything like that.
I mean I'm not even massively qualified to speak on the subject but SF4 is tuned for balance which is something that can't be said for Xenoverse in the slightest, the game doesn't even pretend to be balanced.
Here's the thing I think you're missing. Fighting games have multiple layers to them. They have the dumb pick up and play which is tailored to button mashers. Then they have the enthusiast level, Mechanics and Combos intended for those willing to invest time to learn them, A slight degree of complexity is involved here but it is with any game. Then you have the pro level. Balance is the key here. Everything is built around strategy and and the characters themselves being balanced in relation to each other.
This isn't needlessly complicated it's seperating the wheat from the chaff, It's adding various levels of skill to a game. Xenoverse essentially stops at the button masher stage. It is to fighting games what Crash Team Racing is to racing games.
Plenty of games exist with this multiple level of complexity system and some exist just on one level.
Some examples.
Souls games exist almost entirely on the enthusiast level. They punish people unfamiliar with the mechanics and force people to learn the hard way.
Halo exists on multiple levels. You can pick it up and so long as you can aim you can compete. However those who learn the mechanics, the maps and weapons spawns etc elevate the game to something above just shooting things into something fit for a competitive environment.
Call of Duty is something that primarily sits at the pick up and play level it rewards accuracy above everything else. Long term invested players are usually little better than anyone else. Pro's do sit markedly above others but the skill gap is much less than something like Counter Strike.
It's not an uncommon thing and it's evident in virtually every game, even thing's like chess.
Fighting games are not needlessly over complicated they are built with multiple levels of players in mind and the ones who stick around are the enthusiast and the pro's so the are the forefront of the developers intentions. If you have issues and find something like SF4 complicated then it's because you're not approaching it the right way or with the right mindset or goals.
Xenoverse isn't intended to be a long standing fighting game it's goal is to cash in on hype, deliver a good experience for the players. Focus on making the game entertaining for people to do a run through the story and get people ready for a sequel. It's a fighter only because the source material all but demands it. Calling it the best fighter isn't even a valid statement really. It holds no similarities to actual fighting games. It's shallow and unbalanced and focuses primarily on it's story. It's good and I'm a fan of it don't get me wrong but ultimately it's wrong to compare it to actual fighting games.