There is some parallel with creating the animated show though.
They aren't actually creating the animated show. They are hiring folks to do all the animation and actual production, even if they are providing the voices.
Could they not do the same thing to design an RPG? Hire some of the bigger names in game design to build a CR RPG? Who says that they have to be the designers.
Heck, it's not like everyone at WotC is a designer.
Sure.
But what's the benefit?
They'd lose their D&D Beyond sponsorship. And the players would have to learn new rules and remake their characters.
Yeah, it would make them some money from Critters. But they're already doing that with art books, dice, pencils, T-shirts, hoodies, press on nails, miniatures, comic books, and now a cartoon.
It would cost them a lot of money (paying someone to design and test a game for a year or two) for a very moderate return on investment. While they're huge, they'd be competing with a known name, and not all of their fans would change editions. Because, while Critical Role has brought a lot of gamers into the community, not every member of a D&D group is likely to be a critter. Getting a group to swap RPG systems is a tricky business.
Such a product would be likely to sell well, but unlikely to make much inroads into play.
Because, while...
One rather hopes the rising tide and all that.
Roll20's numbers of games being played have shown that D&D is growing rapidly, but most other RPGs are only increasing at a trickle, if at all. There's a lot of new gamers being added to tabletop RPGs but most haven't started spreading out into other systems yet.
A Critical Role RPG would be a "shelf game". A product you buy to read and then just sits on your gaming shelf...