That's exactly what i'm saying. Thus who cares if it's 'relevant' or 'necessary'? They're coming sooner or later, count on it.
As for the Pokebank example - It was there so Lando-I and Genesect could be put on the chopping block, like you said (IMO the former was kinda kneejerk, but I digress). We have Mega Mawile (Ex-Uber), and the Mega buff to turn 1 speed in tandem with the likes of Mega Loppuny, Mega Beedrill, Mega Manetric and more. It's better to consider it sooner or later.
Also I recall there being a 'No Megas' ladder somewhere in... XY, was it? (or ORAS, I can't remember...), I don't remember that being 'necessary' tbh, otherwise it would have carried over to 7th gen ladder.