As much as I dislike any games without a physical version, it is kind of understandable for MMO's and the like. However, I still like physical discs for MMOs, useless though they may be. I used to play WoW from the start, and seriously from Wrath to the beginning of Mists and despite the fact I never intend to again, I like the boxes sitting on my shelves reminding me of when I did. I popped in for a month last year just to see what the game was like, and I bought Warlords digitally for the reason it wasn't going to have any nostalgic effect on me as well as the convenience.
As far as utility goes, installing from a disc can be a lot faster, and maybe your only option if you have crap internet (I had crap internet that downloaded like crap in my early WoW days, but the game still ran fine). Otherwise, the physical discs don't mean much. I always find it amusing when thrift stores try to sell used copies of MMOs that have had their codes used already and are even more useless.