Its not a unique maya implemantetaion but rather how mentalray works, mantalray can only use all triangles meshes as subdiv or all quads mesh nothing else, period. Not even in other packages lika max or xsi can do it (unless they themselves tesselate and send to mentalray).
So since its a mentalray thing rather than a maya one it isnt fixed in 6.
Tough if you convert it to a subdv collapse a levell (subdiv-> collapse hierarchy) maya will automaticlaly fix the problem, and i asume tahts whet other implementations of mr export do. Or converts to a 3 mesh subdiv, wich essentialy tesselates a bit differently.
so optin 2 would be to triangulate the mesh.
But me id prefeer to get the warning, since splitting up geo to haevier one without me knowing can be a suicide on your rendering/ export speed if your not aware of the problem! And i want the controll, know whats going on, because that gives me the power of optimizing stuff (lets face most mentalray renders can be optimized 2-4 times with tropology fixes and 3-4 times with other optimisations, why would anyone be stupid and not optimize in firstplace).
Why render for 8 days when you can do it in one? This becomes especialy iimportant when you have renders that take weeks, because 8 days might be a no deal but comparasion between 2 weeks and 16 weeks is about as much as getting paid and never seing any money! So if one days optimization can drop rendertime to half of 16 weeks youwe earned a few thousand dollars or rather tens of thousands allready in pure cash.
It makes using better effects viable and makes your customers happier.
