I don't think 'symmetrical' means what you think it means. Just because A makes B 'less urgent' or 'more efficient' doesn't mean we have to choose between A or B. Why not both? Bitcoin Core's dev did not give a good technical reason for not adopting 2MB beyond crowding out smaller miners blah blah blah. I mean, come on. Have they seen the last 1000 blocks list these days?