I think they're supposed to be vignettes. which could explain why the artistic style varies between them. sort of like batman gotham knight.It's Anime by Japanese animation studio's you were expecting something other than Anime inspired visuals? I'd imagine they would have hit up Pixar or any other American/European animation studios if they were going for the hyper-realistic look.
That said, some of the teaser shots for these shorts range from REALLY silly (TOEI) to 3D CG animation (not sure which studio) to Fullmetal Alchemist/Cowboy Bepop style. It's all over the place.
Regards,
SB
personally i'm psyched. i loved GiTS & cowboy bebop, even though im not a big anime fan.