And even like that there are some ready to use system fro some game types like FPS.
Crysis have built in AI taking account of cover points and 3D stuff.You can re use it, and it works pretty well.
last Splinter Cell game had a more advanced AI than Crysis i think, with ennemies searching for you and reacting to sound you make also.

The other style of complicated AI is Strategy, and it could be some real life simulation games also if someone would make some.

After that the AI you'll need will be not so advanced and it's not really necessary, like for MMO, action games, where it's more go to player , attack it on distance and sometimes using some advanced pathfinding system.

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3D has evolved like software.
You had Cobol and such without any Web or interface compared to nowadays, where you needed to take care of all stuff and only specialist could work on it.
Today you have evolved code editors, tutorials everywhere, anyone could produce a software following some tutorials.

That's same thing for 3D, you don't need to be a specialist, you just need to create the game , so have content, ideas, and programming to learn.