Bip110 is not only about the op_return. And the idea of op_return limit lifting to mitigate utxo bloat is controversial to say the least.
Discussion
what's the controversy?
Core is negotiating with the terrorists. They are saying: let's give the spammers op_return, so they don't bloat the utxo set. Bip110 is saying: gfy, we will defend both (and patch other exploit vectors), go spam somewhere else. This is my simplified understanding.