Even if the films of the 80s were on the whole not as good as the films of the 70s, I still wouldn't call the 80s the absolute worst decade for film. IMO, the last decade was much, MUCH worse overall. At least the 80s didn't have endless CGI, ADD editing, overuse of handheld/shaky-cam, or unrealistic high-contrast teal-and-orange color grading.

Back then we had lots of low-budget garbage, but now we have too much big-budget garbage. For example, you listed Death Wish 3 and 4, Ghoulies, and Friday the 13th Part III as examples of the "average" fare of the 80s. I'd still rather watch a braindead Golan-Globus action film, or a Charles Band horror film, or an 80s slasher film than a Michael Bay movie, or Final Destination, or Saw. I can actually physically tolerate the 80s stuff; the 2000s stuff hurts my eyes, hurts my ears, and hurts my head.

That's just my opinion.