Nope, you are right. I can't draft guys to play more games. But, I have traded forwards for defencemen (example) & knew I was getting the short end of the stick. But, I was flush at D and weak at F and needed to make the move to consistently hit the GP limit at the F. There are a few things I don't do with a 70GP limit overall, as opposed to having things split out between F/D/G.
Well there are still 12F, 6D and 2G positions. So having too many of one or the other is still an issue. But you do have a point to a degree.