Obito had no use for the clan, in fact the clan was better off dead than alive. The weaker the villages the easier it is to execute the Eye of the Moon plan.
No point comparing them. Adult Naruto and Sasuke are no longer the main characters so show casing their full abilities isn't important any more. Logically they should be stronger or at the very least just as capable but by feats they aren't.
Whis doesn't want Goku and Vegeta to be irrelevant. Look at how much stronger Gohan was than both Goku and Vegeta in the cell games. A well trained, well motivated Gohan is always far stronger than them