I think that in the end the combining of greaves and cuirass will be required because it can only help with in-game rendering to make the game more stable especialy when theirs a good number of NPC's all on the screen at once.
But heres another speculated thought:
Bethesda said that the "cuirass" and "greaves" have been combined which would include all armor, but what about clothing? Doe this mean that some clothing in the game will still be "shirt" or "pants" and not just "shirt AND pants"? Also I think theres a good chance that even though armor will now be combined that the Creation Kit will still have the "upperbody" and "lowerbody" slots available for all apparol (unless this was also changed) which would mean modders can still change the default armor and add their own created apparol for the upperbody AND the lowerbody.
Just an idea...
:wavey: