I think Doug Chiang, the concept artist for Episodes I and II, had a huge impact on the design aesthetic of those movies (and the fact that they don't have a very OT look). In Episode III, you see a lot more designs that are reminiscent of the OT.
The bottom line is, anyone who cares to create a visual bridge to the OT can easily do so without GL. The artists at Dark Horse do it all the time.