There is nothing preventing the Maya exporter to export Nurb geometry as a Maya specific profile, such as it is the case with many other Maya specific extensions.
You should ask Feeling Software about this, <psurface> (patch surface) could most probably be made available this way.
You are right. Nothing prevents them, but in the end, I believe that NURBS should be explicitly included in the COLLADA standard, just like th e<mesh> element.
The fact is that NURBS are a very good generalization for Bezier, B-Splines as well as other basis. The math is well known and they have been implemented in various systems since around 1983. So, this is not like too cutting-edge.
Plus, they are super-easy and economical to parse - way more than polygons.
Please add them to the standard: they are not just a Maya special case. Then, Feeling can put them back in their plugins and everyone will be the happier
Sure, this will make it way to the standard one of those days. I was just saying that if you are in a hurry you can get it sooner as a valid extension to the current specification (That’s why COLLADA is designed extensible)
And if you do so, then you can provide feedback to how this new feature should best be implemented in COLLADA.