I remember when Wing Commander III came out and I bought a CD-ROM drive just so I could play it. At this special point in history, a typical hard-drive could store maybe one or two CD's worth of data at most. CD's were #$%^ing magical. Suddenly, games and educational programs could make use of video. Truly, it was a leap forward in technology.
Just a few years later, at university, the "brotherhood of the golden disk" was passing around the latest games on CD-R's. Diamond's first mp3 players were a curiosity the rich kids had, and we were playing mp3's we'd downloaded off of usenet on an ancient sparc3 that could just barely decode them in realtime. I splurged on a CD-R and suddenly I never had to delete anything ever again. When AOL discs arrived in the mail, it seemed strange that anyone would just give away something as valuable as CD's!
A few years later, I was using AOL CD's as coasters. I had a storage box built for 5-1/2" floppies that was now full of CD backups of files I'd never look at again. USB key drives had yet to arrive so, if I wanted to transfer tiny source files around, I'd burn a CD and not worry about all the wasted bits.
Today, a lot of computers don't even come with DVD drives. Apple never even bothered to properly support Bluray. By the time BD-R drives came out, hard-drives were an order of magnitude larger. Now they're nearly two orders of matnitude larger. Backing up a large hard drive onto BD-R's now would be more tedious than backing up a hard-drive to floppy discs when the first CD drives came out. Depending on where you are, it might actually be faster to transmit data half-way across the world than to burn it to a BD-R disk.