Thank you for your answer!

Imo the UX issues you describe shouldn't be addressed by Core, but by wallet developers making things more seemless. For example auto-enabling/disabling RBF depending on mempool congestion (enable RBF if disabled when there's some congestion) and hopefully counterparty preferences (there's some discussions around upgrading BIP0021 QR codes to also convey things such as preferred fee and whether the recipient wants the transaction to be RBF-enabled or not).

It's okay to not like a zero-conf service asking you to disable RBF (or waiting for 1+ confirmation if RBF is enabled, but I think it's okay as well for such services to have their preferences and voice them. Trade is always a bargain.