I certainly wouldn't want a system where schools effectively have to dumb themselves down just to appease others. Especially given the shortage of teaching professionals, and support staff across education to deal with the fallout of that occurring. Education as a whole would suffer greatly.
No, its amusing to see middle class parents pulling their hair out because their little "genius" failed the entrance exam and have to mix with the unwashed or pay for private school.
tbh I think in a lot of areas that still have grammars entrance is more of a test of the parents ability and willingness to deploy their capital (social and money) to game admission than grammar enthusiasts like to face up to.
if you want grammar schools what's the right proportion of the cohort to send to them? how much money per pupil should be spent at schools of different types?