not really a format but a structure. There would be a huge mount to consider. seeing as MAX isnt the only thing out there to make 3d with. Making a start by introducing this kind of thing is good though. a 1 shot export for a mesh is only the first step. then u do it for everyhting in the scene into the /mesh directory copy all the rendered textures or textures to /textures etc. thats all i did was get th materials and save the textures and meshes using maxscript. ill try find it.my ideal format would be something more like ogres, with separated files for materials, scenes, skeletons, animations etc...
creating a "chunky" system for something simple is foolish. a lot of the drawback imo with ogre is the "weight" of the whole thing. like using a 1300 cc superbike to ride 1 km to the shop when your bicycle works just fine. what about the guys who wanna just load one mesh? it would need to be a fetaure that is accessible, but not the default. In my view its worth having a system structure that can in essence, "make a map system" from one 3d scene, bt then again u have irredit. Making max export into .irr format has been my route recently and iv found great success.I really wish irrlicht was more like ogre in the way it separates meshes and materials and has a unified animation system
the key is modularity , adding ur mesh writer system into 1 format for a model will make that irr format writer cooler, but im sure you get what i mean?