The sibling comment about lift is one of the few things I can think of. Birds would have a tough time. The freezing point of water would also be lowered significantly.

Eliminating a gas while keeping all other partial pressures constant only affects physical processes. Biochemistry on the other hand only relies on partial pressures, and the number of organisms which interact with atmospheric nitrogen are literally so few that you could count them on one hand.

This is all pretty far afield though. There's no way biological processes are even going to have a dent in the ocean of N2 surrounding us.

Current planes will not be able to fly since they will lose 70% of lift. They will grow gigantic wings.

There'd be less drag on rockets too. That could be a plus for when we need to escape the death spiral we create