Well, you're not wrong. Because mimicry doesn't designate the actual role, everyone has to be ready to act on the mechanics which can be a pain for strategies that you normally have based on them. Likewise, you can't rely on Frog Legs to keep aggro if anyone does anything as all it does is put you at the top of the aggro list by 1 point.

I don't know why they don't just literally reskin Frog Legs to be Provoke, but for the moment you'll have to settle for just working around it until the next patch update for the content where they inevitably put in a spell to outright replace it.