Ok, yes, movies and music have also progressed in hardware, HOWEVER, every movie and every song was not tailor made to a specific system that changed every few years. Think about how big a deal it is to make all these HD remakes we are getting nowadays. It costs a lot, and, depending on the console, can be rather complex to get older games reworked to be compatible with new systems. Transferring movies and music to new hardware is not nearly as complex as transferring video games. This means that many, many video games will never get any kind of official re-release on new systems.
I also have all my old systems. I have a PS1, PS2, Gamecube, and an Xbox, all hooked up and ready to play. However, think about 20-30 years down the line. No matter how much care and effort you put into keeping your old PS2 working, it will eventually break, just like everything else. And Sony no longer makes the PS2. This means eventually it will be incredibly hard just to find a working PS2, just like it is now pretty hard to find a real Ford Model T. Once this kind of thing happens, PS2 game collections will fade into memory, underrated games that never had the chance to be re-released disappearing from the minds of all but the few die-hard collectors.
And one more thing, in all of cinema history, how many radical changes in hardware have they really gone through in all this time? First, we had VHS, then came DVD's, and now we are on Blue-ray? So, two hardware changes since the 70's. Compared to video games, which, according to Wikipedia, we are now entering the eighth generation. So that adds up to two hardware changes in 40 years for cinema, and SEVEN in 40 years for gaming. And I am seeing no slowdown whatsoever in the span of time between console generations.
THIS is why backwards compatibility is important. It's not the same as changing movie formats from VHS to DVD, and it's not the same as records to CD's. If this next generation of consoles were the last one for the next 20 years, sure, I suppose backwards compatibility would be less of a major point. However, as Ubisoft just recently said, they want new consoles even sooner than 6-7 years. So I see no end to this lunacy in the near future.
And with that, /rant