"Hi guys. You've gotten rich off of our platform with your original content. That's great! But we want more predictable revenue so we're rolling out a subscription model. You've got to participate if you want to keep using our service. If not, no worries, go use some other service. Vimeo? Sure, go for it! Whatever makes you happy."
Is it greedy? Maybe. Are they being a "bully"? Perhaps. Is it *fair*? Yes, absolutely, it sure is. They built the platform and made it available for free in exchange for monetizing people's videos (a practice which, by the way, earns the top YouTubers millions of dollars a year). They are free to choose how they monetize those videos, and have every right to enforce that on the users of their otherwise free service.
P.S. Welcome to television, where you pay a bunch of money for a device (TV) and then a bunch of money for a "connection" (cable), just so you can pay even more money for access to places (premium channels, e.g. HBO) that want you to pay money to see a bunch of stuff that you can/must/need to buy (movies on-demand, etc.)!
So, yeah, it's been like this for a long time and at least when you're paying for A: a computer and B: the Internet (and not necessarily C: YouTube), you have 2 very powerful and useful things, a computing device, and a data pipe to the world's information, most of which still comes for free. Most of all you still have *choice*. Good luck trying to choose with your cable company.