Wiki, but yeah. A generation might mean something else than 25 years, but it was the accepted consensus until AOTC. I've tried various explanations...that it's referring to generations of Jedi graduates, or generations are reckoned differently in a Republic/Order that isn't entirely human, different lifespans/birthing times, etc. Yet we're lead to believe SW humans are pretty much the same as earth humans, and time is pretty much the same as earth, even though it would mean Coruscant is almost the same as earth, etc. Anyway, now we have the Republic being re-formed and no wars (to coincide with Sio Bibble's statements in TPM).
As for the downgrading in technology, I don't think we can really take that as true. Yes, when Episodes I and II came out everybody commented that the tech seemed better in the prequels than in the classic trilogy. Now "shinier" doesn't equal more high tech, but for the most part they seemed to have a point. The armor seemed to work, they had bigger guns, their ships seemed better, HUDS were more technological looking, etc. Of course you could say that their fighters didn't have Hyperdrives of their own (had to use those rings) and no mention of fighter shields, but that's about it. Even Darth Maul's ship (in the EU) was said to have a cloaking device (and yes, it's smaller than the Falcon, a ship supposedly too small for one, according to that Imperial officer in ESB) even if he never used it.
So anyway, Lucas tried in ROTS to put things up to speed. When we see that the Rebels were a tiny faction, and that we saw the rich powerful side of the galaxy in the prequels while in the classic trilogy we mostly see the backwater Tatooine and sparsely populated places that the Rebels hide out in (or the primitives on the game preserve that is the Endor moon), and that the Imperial ships and such are supposed to be upgraded above the stuff we saw in ROTS,. etc. It sort of fits. You can blame some of the "look" on expediency.. mass production instead of striving for beauty and the like (the Naboo stuff is designed to be aesthetically pleasing). We see Coruscant, Naboo, and the other planets during the ROTJ SE Celebration and it all looks just like it did before, so no downgrade there. Maybe the Empire cut budgets and streamlined here and there (to afford all those super weapons and giant fleets!)...