For one person to say that their bass guitar sounds better now than 10 or 20 years ago is fine, and I don't doubt it. Seriously though string changes, set-ups, amps, technique, perception, there's just too many variables. When I bought my first good, new bass in 1983(Jazz) it wasn't set-up perfectly well and their was a learning curve on my end in terms of string spacing and the tone/pick-up selection. When I had to sell it 10 years later the bass and I were totally dialed-in, and yea it sounded a whole lot better.(active pick-ups, high-mass Fender bridge, graphite nut, de-fretted) 
