The problem with virtual stuff is there's no way to show it off to your friends.
One reason we buy things is to display ownership. Intellectuals fill their bookshelves with demonstrations of their knowledge. Hipsters show off CD collections of cool obscure music. Fashionistas parade their designer clothes and handbags. The objects themselves have value and purpose: we do read the books and listen to the music. But the display of the object is part of our culture of conspicuous consumption. People are bower birds.
It took eight days to pack and unpack my house on my recent move. I'm still not done; somewhere I have an unopened sixty pound, 1.5 cubic foot box labelled "PC Games". I also have about four cubic feet of CDs. I'm hoping to never open those boxes; the games are installed, the CDs are ripped. I'd rather get rid of the objects entirely, but then I'll lose the pleasure of looking at and showing off my collections.
There's no good way to display the virtual objects we own. There's no online equivalent of looking at a bookshelf full of cool CDs. It's not just vanity, it's hard to casually browse virtual objects, to enjoy any serendipity at finding some long-lost things. It's also easy to forget we own stuff. I just bought Spore online and was surprised to learn from the downloader that I also owned Battlefield 2142: I'd bought it online a year ago. I appreciate that EA kept my bookshelf of games for me, but I wish it were more visible. And unified: I own stuff at Microsoft and Valve, too.
We need virtual bookshelves of some sort, a display of all the digital stuff we possess. There are some precedents. Library Thing is all about showing off your books. Habbo is a whole virtual social world constructed around buying virtual things and displaying them to your friends. And Lord of the Rings Online lets your kinship buy a collective house to display the trophies they've collected. But these virtual collections are so specific, highly mediated, and abstract as to not satisfy the same way as an old pine bookshelf full of paperbacks from your salad days.