Jon: i agree that lots of things have changed...but basics of snow not that much ( level of riders has increased yes too)..
As for lenght: what you get in a 195cm ST for example with a stiff flex pattern ( not the nitros for example), is also a board that is able to whistand very difficult terrains at various speed: the huge nose acts as a bumper and eats all the bumps, cruds etc that you get after an avalanche, or after the snow has been tracked a lot: its a bit like those new high speed 4WD that just float while bumpers do the work.
I'm not sure a shorter board aka 165-170cm range will have the lenght to master this ( short bumper in a way)..The main difference between modern ST and the Winterstick for example is in the flex and how the flex makes it possible to carve, absorb bumps, relaunch ( flattens the board back) after turns quick etc.. The shape is basically the same as its been for the last 25 years.
Also a big plus of the ST is its STail...faster you go more control you get like a fin in the water but no drag. I have tried a long freeride once ( not as long as 195 ok) and felt the faster i went, the less easy it was to be on the tail for it opposed pressure and would not sink...
cant wait for snow