Actually, the PSOC does just that. You get x number of analog and y number of digital blocks, and you get to allocate them as you see fit. Seems like a real neat feature to me.

The biggest reason I didn't investigate further is those chips cost as much as an expensive pic. I guess I'd rather use a more affordable device that is designed to do the job rather than an expensive one-size-fits-all that has no other benefits.