Value?
Silly as this may sound, but the size of the frame affects value big style. Smaller frames always fetch a lot more money, as generally there were fewer of them made, as back then frames were sized more like road bikes and in truth were too big for the folks that bought them. Today people are realising this and wanting small frames.
I have seen large size top end Ti frames go for peanuts and small size older and tatty crmo frames go for big money. Cycling as a sport strangely is also more popular with smaller people! Weird but true.