Of course they aren’t terrible. They’re just terrible compared to the originals.
Even compared to the originals, they’re not that bad. ANH is great, ESB is okay, and RotJ has some glaring issues, but is otherwise enjoyable. TPM is really fun (save for some bits in the middle (mainly Coruscant)), AotC is a slog (the only SW movie I might say is genuinely bad), and RotS is a freaking masterpiece. Overall, I don’t see any overall difference in quality between the trilogies.