A number of airlines do this - Austrian for sure. It's about EUR15 per leg so not cheap, but then you just end up on a slippery slope again. The price goes up & quality comes down as the bean counters recognise it as another profit centre.

It's being reported that IAG is now running out of margin left to squeeze - this would simply add a bit more to the sponge for them to wring dry. The end result for passengers won't be good.