I don't think I'm fond of the concept. I have a hard enough time finding RPs that catch my eye, and being forced to play a character I didn't conceive means it's likely not going to be one I feel invested in. I've played canon characters in 1x1 RPs due to partner requests, and I felt extremely confined the entire time. Having a pre-determined character murders player creativity and choice.

And let's say you have a game with rigid roles, what happens when someone playing an essential role drops? You just sabotaged your own RP. I've been in a few games where characters had to fill roles like a prophecy or whatever and as soon as the GM lost a few of these characters who were supernaturally selected to save the world, it completely derailed the entire RP's plot.

I treat games like no singular character is essential. Everyone can come and go and the plot remains intact, and all of the RPs I've been in that have been multi-year runs have involved highly involved players who went through an audition process and came up with some really incredible characters with a lot of emotional and personal investment. I can't imagine that same community forming from a game where the GM decided who everyone is before hand and players are forced to puppet the GM's husks.