I don't think resistances are useless.
Lot's of people complain about them but.
Whenever I give up a damage item to buy a defensive item, I notice a damage taken decrease.
Buying a Seeker's against Zed and Talon is very noticeable to me. It basically fucks over their Dirk purchase. Grabbing an Abbysal Mask when facing ap characters has a noticable impact.
If I'm building full tank, it feels like I'm a tank. The enemy takes longer to kill me. When I play Amumu I can survive like 15 seconds of constant DPS as long as I'm not being hailed on by Magic Damage. Armor against a full AD team feels noticeable, it doesn't completely fuck them over, and it shouldn't, but it does make me more survivable.
Maybe resistances could be better, but I think people honestly blow them out of proportion when complaining about them.
