As one that uses warmups I don't feel in the least shortchanged because the AI doesn't warmup their RP. I do it to add challenge (it's not really very challenging) for me, and I'm sorry, would doubt the AI's ability to handle it correctly. Just because other games have had it doesn't mean it worked well. It's also fair to say that my doubting of the AI doesn't mean it can't be done and done well.
I would actually fully support OOTP adding the feature whenever the coders feel it can be done well. Having said that it wouldn't be anywhere near the top of my personal "want list". It it were to be added I would request that there be a separate on/off toggle for both human and AI. IOW I want it so I can turn it on for me, but off for the AI.