As it is, you need to go to the game's own page to add it, which requires you to find a link to the game by searching or browsing, unless you somehow remember the game code and the proper URL form.
Also, the buttons to add games to your lists are down the page in a small box, which can be really hard to find for those not familiar with the system (at least it was for me).
I do know of at least one user, vaio, who agrees this is a pain to work with (he hasn't added many of his recent games because of this). And for this site, it does consume bandwidth.
Now I don't know if it's practical to change the system, but I at least propose we could add an "I own this" checkbox or button to the search results list, so we don't have to load up a new page (especially if there are multiple items we own in a search list).
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs