Given that one of the mechanics AIs have only availible to them, Advanced Programs, they inherently suffer from a lack of playability as only decks, RCCs, and drones are capable of running them. This resource gate limits the chargen possibilities of AIs, making deckers or riggers only viable. Additionally their Emulate action is counterintuitive to this. If you are capable of "faking" a matrix attribute why bother having a device with one? Yes you'll want a place to "rest" after a long, hard day, but even that is difficult by design as your Depth defines what device you can or can't load on to. Presuming you want to be flexible in device choices you'll need a lower Depth, which in turn handicapes many other AI mechanics such as known programs or Emulate. Logically there are too many competing factors to allow AIs to be playable within the realm of relevance outside of the smallest handful of builds (second to TMs, natch).