My issue with the PT is that it ends 20 years prior to the OT and yet the designs (of everything not just ships) seem like they are cut from a completely different cloth. It just doesn't feel like a society should have changed so drastically in such a short time.
That was the point! They were supposed to look like a society who was putting more design and artistry into the ships, vehicles, architecture, etc. Once the Emperor takes control that goes down the tubes like the Dark Ages. Some rich Imperial worlds may have continued this trend in some ways so you might see fancier stuff there. So if you go to Coruscant you may see the same fancy personal speeders and things. The rest of the galaxy was just trying to get by without, as Obi Wan put it, any Imperial entanglements.
I don't find the shift in style weird, but you'd think more of the fancy PT stuff would still have survived into the OT era. 70's cars looked a lot different to 50's cars, but you still saw a lot of 50's cars on the streets from people who couldn't afford a new one.
But I guess in the case of SW, they were on different planets, so it's not a big deal, there's just a bit of a mental disconnect not seeing that lineage for some of those designs. Comparing the scope of present day Earth to a galaxy of planets is probably apples to oranges here.
I didn't really end up having a point in all of that. :wacko
We talked in another thread about why we aren't seeing more Republic era stuff, military at least. My guess is that the Emperor had everything tightly controlled so they weren't going to lose a Star Destroyer or anything that would give the resistance a hand. We did see a Juggernaut (aka Turbotank... sigh...) in Rogue One in use on that prison planet. I'm thinking that they kept some older ships like Acclamators or Venators for patrolling systems on the borders. I would like to see a future OT era show have a Republic Gunship in use or maybe some clone trooper armor on the Rebels.