Opposing a feature request because you 'worry about the balance' is childish and annoying. It's a deadweight opinion based on an entirely selfish desire to cockblock others for no reason whatsoever.
TL;DR, I've yet to see any valid reasons to oppose this idea. If your only concern is balance, just say "I'd wouldn't mind as long as the balance is done right". Don't go round saying "I oppose this because I worry they might ruin the balance for a situation I never intend to play". It's really selfish. Stop offering dead weight opinions and use your head. There is a very simple solution to this and would be trivial to keep everyone happy.
It's especially jarring as a bogus argument because, among other things, it seems to assume that currently the balance is in a state of Holy Perfection and nothing should be done to upset it, which is obviously silly at best.