Some explanations from Steph :)
Objects are optimized so some surfaces are erased because not necessary when other objects are embedded inside it
In real time each polygon count :)
If a closed surface is good normally when open it direction of normal must be keeping (?)
During modelings of some new objects (in Moi )some curious strangeness things appear
boolean don't want work or inverse them (diff become union), chamfer don't work but filet yes (for a same object)...

And yes C4D can makes UV :) (see image follow)
(or works upon normal) But one more time it's more effective if Moi can make UV (or normal) from the Nurbs Export Obj because when you have 100 objects to remake by hand
it's some painful :)
And Auto UV like Zbrush are not practical for toshop for example
Ps @Sk2k : and sorry but Plug for Blender to hyperion are not planified :(