That's what I already said above, but what you're missing is that the discs are so huge that few things will require that much space. For those applications, other media or 'net distribution will take over. I venture to state that few software packages will ever be distributed on BD.
It makes no sense to ship a physical disc capable of holding 30-50 GB of data for 500 MB of data, so the uses for the physical medium become fewer and fewer as the media size increases.
B
Funny, I've heard the same argument in the past.
"why would anyone ever need more than 512k of memory?"
"a CD with 650Mb of capacity is just HUGE"
"a 20Gb hard drive is just massive, no way I'll ever use that much space"
Want to know where all that space will go? Try a true HD movie with uncompressed audio, not the 720p that Apple is renting. Even so, 720p still takes up 4GB. Try source video at 4k resolution. Try photo realistic 3d modeling. Try an audio collection using lossless encoding, not FM radio compression. And those are just off the top of my head, for uses TODAY. Who knows what it will be like 3 years from now. Knowing Microsoft, 20GB install for MS Office can easily happen.
As for net distribution, yes it will become common. In 5-10 years. 40% of the US still uses dialup. And broadband is still ~2mb. Your going to need 10-20mb for true cloud computing. And a reliable network, not something that craps out 4 times a week. I'm looking at YOU Time Warner Cable.