>>2318564The S2 Gundams are new designs commissioned by Wang Liu Mei to the CB design team led by Ian (she was said to have pushed for the creation of the 00 Gundam afterall).
And as to the simplicity question... detail simplicity is actually a very good sign of technological progression, since it means the internal tech is so sufficiently advanced that the external appearance doesn't need to reflect the complexity of the equipment.
My old DVD player nearly 5 years ago, which was as large as a CPU tower, had all manner of hatches, buttons, and knobs on the front to operate it all its features. Now my latest DVD player is just a small smooth, black and silver slab with only 7 buttons. It has less detail than my old DVD sure, but it's more advanced and has more features.