Let's just say as a 90's teenager, I think 80's music gets a bad rap is more on how music technology was used. Synthesizers, electronic drum kits and new technologies were a boom during that time .... most of the music beforehand was produced on analogue instruments.
When you have a band with a lot electronic instruments of the 80's, that's where you get a dated sound whereas quite a number of 60's & 70's music has aged much better due to using analog instruments. When you can put a sound to a period, that's when you might think its cheesy so to speak. Its not to say 60's/70's recordings were better (in fact many are horrible and in mono), just that some of the recording techniques are still being used for modern day recordings (eg. Foo Figher's latest album) and the technology has moved on such that you can emulate vintage sounds even though its a digital recording.
Someone mentioned that 80's was full of manufactured pop bands, this hasn't changed since the advent of recorded music. Even in the 50's, 60's and 70's there were thousands of copycats & one hit wonders. Its just that the 80's helped expose the level of how the recording industry works with the invention of the music video and MTV. Since you could sell more records with a single that has a video, this double exposure of radio and television brought huge sales for record companies which in turn lead them to find similar products to make money off.
To me, every period has their gems .... I like Elvis, I like 80s new wave punk, I like 90's grunge, I like 2000s metal ..... living throughout some of those periods there are a number of things I've outgrown and now find not as good as I remember it, but there's a whole heap of old music I have discovered and liked. Its really a matter of taste
So for me its not that 80's music that gets a bad rap, its a combination of 80's music technology, how it was used in popular music as well as the creation of the music video that helped define that period.
