Oh, that one again.
The armor system is very similar to Oblivion’s. The main difference is that the upper and lower body armors, the cuirass and greaves, have been combined into one piece.
Yep, just like Oblivion's armor system was very similar to Morrowind's? And in TES 6 they say the armor system is very similar to Skyrim's, only that boots and gauntlets have been merged with the armor.
This helps create armor styles that have the look they needed for Skyrim.
Valid reason, actually the only valid reason they have given. Hope they make use of it and the armor designs are really much more interesting.
In most of the Nordic designs they created, the upper armor would completely cover the lower armor, making it unnecessary.
Looking at the screenshots the upper armors don't cover more or less of the lower armors than it was the case in Oblivion. If you wear no upper armor or clothes like shirts it doesn't matter anyway.
and it renders a lot faster too, so they can put more people on screen, so that was an easy tradeoff for them.
Ridiculous excuse. Just look at the armor variation all people are so excited about. Those are separate pieces as well (in game engine terms) and they have a lot more polygons than separate greaves/cuirass meshes would need. That alone crushes all the really silly arguments the devoted fans come up with why a few polygons less and one armor piece less would make any difference at all in rendering performance. This one is simply a lie or at least a heavy, heavy exaggeration.
They can also make a lot more armors now, so the number and variation types are more than they've ever had.
Yep. Because adjusting the armor meshes to make them separate takes almost as much time as creating an armor from scratch. < sarcasm
I have accepted that armors are merged and it's not the end of TES. But the only valid reason why they merged them is that they wanted cool looking armors and didn't care about one additional slot. It was easier to create the armors they wanted that way because the concept artists/modelers didn't have to think about matching cuirass and greaves while designing the armors. That's an ok reason, although I would have preferred separate armor in exchange for a slightly more 'generic' armor look.