When Merion and Shinnecock and Winged Foot were lenghtening their tees, it was in response to a modern breed, several generations in the evolving, that had made these championship venues too short for U.S. Opens. Somewhere between the appearance of Jack Nicklaus and the appearance of Tiger Woods, the courses of Ben Hogan's day were no longer adequate to test the best players.
I don't think those changes were made solely as a response to improved equipment -- but the current round of lengthening is a result of technological advancements, nothing more, the next round will be a response to unchecked technology as well, and the next one after that. Humans can't improve as fast as equipment can, especially given the USGA, R&A and PGA's current lack of control or will.
I think the Johnny come latelys are responding not to the lengthening as much as the speed with which extra yards now become necessary. St. Andrews lengthened, what, six years or so ago? Will the next lenghtening be necessary in three years?
I think as amateurs, we also have a decision to make. If the pros will not leave the classic courses alone, then we'll have to identify new classics that will not host pro tournaments. Just because the very highest echelons of the game are going in one direction doesn't mean we have to follow -- and that goes for any classic course membership that chooses to get off the distance merry-go-round.
One other point, responding to Matt's question about what kind of equipment is used by those who most loudly object to the advancement in club and ball technology: I use whatever's legal. My gripe about the equipment has nothing whatsoever to do with how far my ball or Tiger's ball goes; it has everything to do with what St. Andrews decides it has to do to keep up with it.