http://videogamecritic.com/forums/viewtopic.php?f=5084&t=10849&hilit=bit+rotWe have had discussions like this. I recall a difference of opinion, as some gamers point out their floppies are still going strong.
I don't know about optical discs, but magnetic storage like tape and floppies were never reputed to be robust. I was always warned against all sorts of dangers, from pencils to magnets. We all had our floppies in those little plastic boxes that held 10 disks, otherwise we had loose floppies with lots of pencil divots in them.
I think it's amazing these floppies have lasted this long, but I'm more amazed so many games have been preserved in other formats to play on things lime 1541 drive emulator hardware like the SD2IEC you attach to the vintage computer to play. Unfortunately, other things like games on tape files are preserved, but still need to be treated like audio tracks to try to load them in. In this case, I would like them preserved but in a more useable format.