I agree with a lot of what you said, but the fact is that synergies did make more skills useful that weren't before. Your idea to redo "useless" skills is a shitload more work, and I'd definitely take synergies over no change at all. BTW - Grim Ward is useful, for example, I use it to kill enemy groups faster because it lets my barbarian focus fire better.
The real issue is that a lot of the difficulty of the game was destroyed online by bots. It was too easy to get good equipment and fast experience, which I say because you think the high end sets are jokes.
The immortal king set is really good. You can pretty much not be stopped when wearing it, and it's possible to do /players8 hell solo with it, as long as you are careful.
I mainly played d2 on LAN with people I know, enforcing a no-cheating atmosphere via peer-pressure, and I wish they would just make more expansions for d2 instead of an entirely new game.