False premises.

They are not all the same. Though subtle, each model in a class has
its peculiarities. For example, the LS-8 is a better climber than a
D2. The Ventus 2 is a better climber than the 27. This translates into
differences in tactics. The 27 and D2 are better suited to meandering,
the 8 and V2 to saw-toothing.

There is, in fact, more than just a subtle difference between models.
Cockpits are shaped differently, the low speed bucket is wider for
some models, dump rates vary, handling varies, all of these factors
shift the spectrum of pilot options for a given situation. There is no
doubt that some model families are better suited to a particular pilot
than others.

And I won't even start on the advantages of optimizing wingspan. A
savvy CD could easily design tasks that would cripple any glider with
less than 20 meters, regardless of how heavy the 15M racers.

Of course, that's not to say that your idea isn't interesting. But
your foundation is weak. You need another, better reason to launch
this revolution. (:-D