So, if a group of people enforces their preference on others, that is okay, or what?
Nobody claims that there is "some secret vendetta". Dodging at the current system is basically blackmail, but that is a different question. The only relevant question is, whether the majority of players is entitled to implement a system, where the minority cannot play their favorite maps at all (because queue times will inevitably become intolerable), so that the majority can play 10/10 Arabia instead of 9/10.
In sociology it is called "protection of minorities" ... and you can call having to play 1/10 non-standard maps "forcing an unpopular choice on the majority of playerbase" as long as you wish, your argument does not get any better. At least in 1v1.
TG is indeed a completely different problem.
The whole discussion from my side is about TGs but same is applicable to 1v1 as well. People like what they like, everyone should have the option to choose based on their liking. Great if many others share similar preference as you and sucks vice-versa.
Minority protection is covered because the choice of non-standard map is available and no-one is taking that away. Its a fact that very few like those maps but that's more on the map, nothing else. I don't want to play Amazon Tunnel or Water maps, ever (not even once), tell me one reason why I should waste my free time on a map which I find completely bogus.
People play ranked TGs to play with others of similar skill to have balanced matches. If there was any other way to do this, I am sure people will just move out of TG MM.
If we were to implement opt-in I would expect wait time distribution to be something like this (exact numbers will depend on player base).
So not only wait times for Ancient, Mocha etc are longer but the matches will be less balanced as well. This is simply because not a lot of people want to play those maps. But for those who want to play the option is there.
If the map is good it will eventually grow in popularity, it happened with Vertigo already.