is knockback rude?

[Niwashi]

I only use knockback in PvE if:

A) The target is already close to a wall and the knockback is negligible.
B) I know the target is immune.
C) It is low on health and I know the knockback will kill it.

I'd add a couple more to that list:
D) Necessity if the mob's coming after me and no melee players are on it, but I need it away from me to survive.
E) If it's casting something that really needs to be interrupted and the only interrupt I have available is a knockback.

But they're still all very specific circumstances. Throwing knockback attacks into the mix regularly, and on mobs the tank or other melee are attacking would be rude.

(When soloing, though, knockback attacks sure come in handy a lot.)