if only to show that I don't do only mesh enablement workaround forum posts, I'll reply to this with some details:
We show mesh objects as a Prim placeholder for non-mesh enabled viewers. The type of prim is based on the number of textures used, because we need faces to hold each texture. We had a fancy solution, but in the end actual features and bug fixes trumped them in priority.
Not showing them at all is problematic for a reasons including naked avatars and invisible collision.
I can't speak to TPV adoption timelines, although I will say that they had access to our code throughout development.
Regarding lack of support for newer features (like mesh) in v1.x based viewers; I can't speak to people who continue to ride horses down Main St. and curse at the those horseless carriages swerving around them.
Cheers
Charlar