Pat-i would say that overseeding became a systematic thing when people in transition areas realized that they could keep the courses green all year by throwing out some seeds. My super once said, 'Its not that bad to get back to bermuda, just have to use more fertilizer.' Then, once one course uses it, in a resort style area, everyone has to use it so they don't lose business to those courses that do. But in say, Boca or Miami, there is no reason to use overseeding, its simply stupid and a poor expenditure.
--also, could clubs in the S. Fl. area not use paspalum? I know they use it in areas of the Dye course at PGA Village, and it sure seems to stay green in winter, though I haven't yet experienced what it does in summer.