Well, you have to take into mind the context with which many people are entering the discussion. Going back a year, I was completely against the notion of DD being the direction the industry should go, and there were several reasons for that. One is that I was a console gamer where there were very few instances of DD and retail being an option for the same product. Also, the DD option invariably would cost the same or more if it did exist. Being on a slower connection back then, the argument was a no-brainer. I could pay the same amount, wait hours for the game to download, and end up with a copy that couldn't be easily transported (if I wanted to take it over to a friend's house, for instance), couldn't be lent out, couldn't be traded in (and so on), or I could drive the measly three minutes to the nearest store, buy it, and be playing within fifteen minutes. It's for these reasons that I think DD-only is a non-starter for the current mindset of what console gamers have been used to for the last two to three decades.
But move over to the PC side, and it's a completely different story. But this is also why there's been a lot more progress for DD on the PC. Resale is practically an alien concept there, swapping discs is an annoyance since most people to a complete install to the hard drive, and the two to four players sitting around the TV for multiplayer setup commonplace on consoles is very rare, there (thus mitigating that 'I like taking the game over to a buddy's house for game night' argument). There, the concept of disc ownership is largely unimportant, and to that end I wouldn't really miss PC games not being at brick and mortar stores. It also helps that my internet connection is faster now (and uncapped), and I now live further away from the big box retailers than I used to.