It seems that, among the players and groups I know personally, there was much more reluctance to switch from AD&D 1e and 2e to D&D 3e than there has been to switch from D&D 3x to D&D 4e.
Now isn't that funny? My experiences have been different. Yes there was a reluctance to switch from 1E to 2E. No reluctance from 2E to 3E and even more reluctance from 3E to 4E (more so than the switch from 1E to 2E I dare say), but this has been my experience and is not an accurate sample of what's happening out there. I guess it's just different wherever you go. The groups I have been involved in during my 20+ years of playing D&D have come and gone but I have been cognizant of their reactions to the edition changes.