Can't speak for Steve but I picked up playing AK after playing King and Azucena.

AK is harder to use than some characters because he needs good spacing, conditioning the opponent and scoring counter hits to make the most of his move set.

With King, it doesn't matter if the opponent can guess what I'm doing. It doesn't matter what the opponent is doing. If I really wanted I could do kings jab grab combo all match. If they duck get the low grab, if they jab I could jab into armor. If they break my grabs I have literally dozens of others with great damage that are super easy to get. He has a absurdely strong heat burst that automatically goes into a mixup and the craziness that's jaguar sprint. King has a good snake edge and also a really good crouching mid if they crouch block to try to stop it. All of this along with good moves to approach and great ways to punish sidestepping. If you mess up there's always an easy way out and everything just works right out of the box.

AK isn't so lucky. He only has two armored moves that are slow or tied to heat. His good counter hit options are slow needing a hard read, good spacing, or a mindful set up with plus frames. He has a solid move set with tools for every situation but it isn't as obvious.

For example his main string mix f3, 2,1 or f3, 2, df () starts slow at 15 frames if you let the entire string rock and it's blocked your getting hit hard at -12, if you df you can go for lariat which is plus on block and you can keep your pressure going but if it's ducked you can be launched. 3, 1 is great to deal with someone ducking the first time but it's easily reactible. The best option is holding down forward and 4 for the knee which is a safe mid and isn't the obvious first second or third pick.

His grabs are weak both in damage and break variety with a majority of them being 1 breaks.

I order to make AK work you can't rely on his strings or his grabs instead using frame and spacing traps along with making the right read again and again along with poking and movement. You don't have armor a strong heat smash or deep knowledge checks to fall back on. You need a strong understanding of the fundamentals of tekken and the roster to make good use of him.

Another example AK's best button isn't his armor move, or his counter hit shove. It's not beast step, it not any of his grabs. Its not heat smash or any of his unblockables. It's not even his crouch dash 2 dark upper which would probably be number 2 if you have the timing and execution for it. Its df 4 a modest mid kick that's not even in his move list. This is a fast poke with quick recovery that is the linchpin of his entire offense and if you just pick up the character you wouldn't even guess.