Maybe setting custom fees is too risky, many users will ignore the warning and mess things up by sending txs with ridiculous fees like 50 satoshi fee or so (not per byte, but in total 
). And then complain about their tx never coming through.
). And then complain about their tx never coming through.If users were made to jump through a lot of hoops to get to a custom fee setting window it's unlikely inexperienced users would use it. The devs could also add some code that compares a custom fee with the dynamic fee and warns about excessively high or low fees when someone tries to send a transaction. Other wallets already implement such warnings.