YouTube is a weird one, personally. Why shouldn’t it have a subscription based service like any other streaming network? Because the content is not created by, funded by, or even necessarily supported by YouTube.
It would make more sense for the subscription to be put upon uploaders to host the content, since their business is hosting the files, not really the content itself.
Now, if they had a better or at least more transparent way of giving the creators a truly fair cut of the monetary gains earned through their videos I would have nothing against YouTube Premium aside from hating that a completely free service has to move to a paid service.