sk8mate:
It's definitely interesting to see how training advances have bettered athletes. However the girls with the "thunderthighs" still have more height and power to their jumps than the smaller girls. None of the thinner skaters jump like Midori and Tonya. In fact, larger skaters such as Sebestyan, Slutskaya and others have more height on their jumps than Sasha and MK. It would make sense that girls with heavier muscles would be more explosive than girls with lighter muscles. If you look at track and field, the sprinters are extremely muscular b/c of the power needed for the start while the distance runners are extremely thin. Same thing for swimming as well.
I think the reason why the girls are getting smaller is that it's easier on smaller bodies to complete multiple triple jumps without injury than larger girls. The bigger girls get more height on the jumps but their bodies have to bear a harder impact. It's interesting that as another poster noted, the men are getting smaller as well. Skaters such as Jan Hoffman and Robin Cousins were significantly larger in build than the skaters of today.
Also skaters seem to eshew weights in favor of Pilates (both guys and girls) which would explain why the muscles are leaner.