It may not be applicable in all games. But there are many games where the AI skill matters a lot to players. Or where they just get annoyed or bored with stupid AI. Games with bad AI (which is most games) frustrate me a great deal.

AoE 2 let players make their own custom AIs. They took one of the best fan made AI scripts and made it the default AI in the new release. And players loved it. Because it provided a much harder and human like challenge, and didn't cheat like the old AI did.

Obviously you shouldn't just train an NN to instant headshot players with optimal strategy. You can add realistic handicaps to the AI like noisy controls and human reaction times, so it isn't superhuman.