It’s a tempting idea and one that’s come up before.
I think it would be less damaging in terms of “the painted duck effect”, but I’m not quite sure I understand the problems its trying to solve.
One person did mention awhile ago that they’d like to mark “special” tokens via a symbol on the token body itself. I’m not quite sure what the criteria for specialness is though (my guess is the big bad boss?).
I’ve also heard requests to use them to track status effects.
What problem are you hoping this would address?