I'm not sure of your question. It's true that cycling is driven to a fair degree by marketing and not all improvements are improvements, although some certainly are.
However, practical quality of bikes hasn't risen much, and has certainly risen at a slower rate than inflation. A $500 bike today will probably work more nicely than a $500 bike from 1990, although mainly because of on-bar shifting.
I'm someone who likes lots of things about older bikes - my two main road bikes will soon be built around Centurion frames from the 80's, with threaded headsets and quill stems and square-taper bottom brackets and horizontal dropouts (I don't think all of these are better, especially the horz. dropouts, but it all works quite well for me). But I think on the whole, you're vastly overstating things.
Last edited by TallRider; 12-09-06 at 10:24 AM.