The problem with digital games compared to physical is a lack of true ownership/control. If I have a Mario 3 cart, I own Mario 3. I can play it on any device that runs NES games, I can dump the rom to make my own digital copy, I can get a new system if mine breaks and all is well.
Digital games do not afford us that freedom. For example: you can't download Scott Pilgrim Vs. The World anymore. It's simply not in the marketplace. I have a digital copy on my 360. Does that make it a cool, interesting thing for other gamers to see? Well, no. I can't lend it to them. I can't sell it. I could put it on a memory card/flash drive and copy it to another system... but without my profile for Xbox live to check against, it's useless.
Assuming that someday, we find a way to crack into old console hard drives, past the checks & restrictions & copy protections, then maybe it'll be a big deal. People will comb flea markets, buying half-dead units to dig through their data for long-lost games. Without that, digital games as we currently know them will simply be a thing floating on some old hard drives in the closet, while cracked & pirated copies get traded freely.