Pat,
I agree with others that the creative juices are inherited. Now, maybe school refines that or provides a framework to work within, but really, I always knew within a week whether an intern was really a design type personality.
As to your suppositions in the OP, actually, and with all due respect, they are mostly BS and generalizations. I say that any gca who wants keep learning from others can and does so. ASGCA meetings are great, and we learn from the courses we play, seminars and discussion of those courses and issues, and mostly from hanging out with others who (as Jeff alludes) can get very philosophical after a few drinks in a loose atmosphere.
Of course, it can happen other ways, too. Archipalooza (the one I was invited to, anyway) was a similar atmosphere.
Over Thanksgiving, Rich Mandell was in town and we spent a few hours at lunch exchanging ideas on gca. I have talked with Ian on the phone on several occaisions. Frankly, I think we can learn a lot of ways.
In reality, we have a few photos of the old guys doing other site visits, and from that you extrapolate that these guys did it all the time. Well, I recall someone who knew about that famous Mac visit say that he only went there thinking they were offering him the job, not much different than what might happen today!
I do find it hard to host or be hosted on a job site, but I have done it. Like TD says, you fly in to work, you are on a limited schedule, and gasbagging about architecture with a peer doesn't seem like my best use of time......