I'm inspired to respond to BigBarada (above) and haven't read JT's statement at this moment. Just trying not to lose my thoughts.
I liked the idea of transitioning to OT ships by AOTC / ROTS. I think the militaries of SW could be shown constantly evolving. (Totally agree with you about the coolness of the AT-TEs. I wanted a toy the moment I saw it - completely falling for Lucas' merchandising trap but enjoying the journey like most of us here.)
AOTC saw Slave-One arrive - which is great beause some ship should not transition, like you still see old Buicks and Oldsmobiles now and then on the freeway.
Landspeeders and taxis wouldn't change much. The triangular shape of Jedi starfighters and Republic assault cruisers was an enjoyable addition.
Also the Correllian Systems Engineering ships with the rows of horizontal engines like the blockade runner were great to see since Episode One's Radiant 7 and Palpatine's diplomatic cruiser.
Now the Trade Federation converting those ring-like freighters to assault and invasion carriers was a great and creative idea that would be very plausible considering what they were and how their military plans were evolving.
I need not mention the walkers again, but in the comics, AT-ATs out of Balmorra were also deployed as early as the time they were using AT-TEs. That also made sense. I think the flatter ones were more practical on Geonosis terrain for better balance and lower anti-personnel guns good for fighting battle droids on foot.
I think we didn't see (Republic) gunships on Hoth because it was too cold and on Endor because there were too many trees. But I'm sure the Empire still had them. They said the speederbikes on Endor were really old.
Because of the toy's features (CW release versions) I'd like it if they'd said the ROTS Jedi Starfighters actually were the Delta starfighters of E2 / CW after they had been hit and refitted for service, with parts missing. In all honesty, the ROTS versions looked to be better, more maneuverable ships than the AOTC types and the EU says they are actually made by different (fictional) manufacturing companies. Lucas just wanted more triangular ships like star destroyers I suppose. But AOTC did have star destroyers at the end at any rate.