I haven't paid attention to player-simulating bots in online shooters in forever, what are the current issues? I'd argue that players are a bigger issue, e.g. cheaters, big skill gaps, or the fact they keep shooting at me.

There's singleplayer games, but those are intended to be gameplay challenges, not simulate other players. And in that area, I haven't heard any "this is really good" since F.E.A.R. which is nearly 20 years old now.