AOTC and ROTS look totally fine to me in terms of picture quality; I mean it’s not like they look like 28 Days Later or something.
28 Days Later looks that way on purpose (I assume, I don’t know anything about picture quality).
I mean, if you’re saying they chose to shoot it on a shit camera, sure.
They chose to shoot on cheap DV. Whether that was a good decision or not, the aesthetic choice was pretty deliberate. I assumed it was much like the idea of shooting on grainy 16mm to give a specifically gritty look.