Virtua Fighter 4 perfected single-player years ago.  Aside from a Quest Mode with AI based on actual players, VF4 and later sequels had extensive tutorials, including character-specific ones. I remember Street Fighter Alpha 3 having a World Tour mode along those lines as well. 

So why don't more fighting games have those features?  I'm guessing that now that there's online play, people would want more focus on netcode than on AI,especially since people will only play single player for a few weeks at most. Fighters died off because of the shift from arcades to consoles, and VF4 and SC3's extra modes didn't do much to replace the fun of a random stranger challenging you to a match. 

As for SF4's AI it's terrible.  A lot of characters are set to use Focus Attacks when you're about a body's length away from them, so you can get by just with your Focus-breaking special attack. Another example is Abel, who at that distance is set to use his roll into a Tornado Throw. Again you can exploit this because Abel can be thrown out of an non-EX roll.  Even Seth does this: Either sit full-screen and wait to anti-air his Wall Jump or go to midscreen and wait for an unsafe spin kick. Works no matter what difficulty it is.

I remember trying out Virtua fighter 4. As good as many of it's ideas were it still wasn't quite the game for me. Didn't have any character I particularly liked and the fighting was so technical it was almost impossible for me to learn even with tutorials. Glad that they tried so hard though. Most game makers don't even bother. I might pick up a copy of one of the games to give it a second shot since it's been quite a few years since I last tried.

As for street fighter's exploitable AI. If you don't know how to exploit them (newb) then you get greased. If you do know how to exploit them (hardcore player) then you get bored. I wish that game makers would put more effort into single player because I really really hate fighting online. I just end up running into people using the exact same strategy with the exact same overpopular character and beating me over and over because I am playing as someone I like and have no set strategy.

Sucking isn't fun. So the games need to help me not suck and give me something fun to do when I am in the process of sucking.

Jeffrey, I feel I am a lot like you in that sense. For some reason I love fighting games and will typically mop the floor with newbs, but anytime I try to play competitively online, I suck at games.

I think part of the problem for me though is that I focus on what the combos are and don't react to the way my opponents attack. All the offense in the world cannot make up for my lack of defense. 

The only fighting game I could compete in was Capcom Vs. SNK 2 and that is because I trained with a friend in my college dorm. The dorm had a fighting tourney every year and for once I didn't want to fail out early. Sure enough, after I had the combos set in my muscle memory; I focused on defense and made it to the semi-finals.

Thanks for letting me know I am not alone.

Yeah Sean I feel you. My lack of defense is a huge reason why I suck at fighters. I can't react very well to the animations so any attempt I make to block or counter is usually guess work. and  most times I guess wrong.

I've mostly played single player. Only time 2player was a triumph to play was when facing off an equal rival (cousin) on MK2. Finding the perfect live opponent is difficult, mostly either a newbie or hardcore player. SC3 single player game was a blast, spent late night hours unlocking and perfecting my picks.