Definitely with you on this. No way would I backpack it on a resort, just something wrong with that picture.
Hmmm, lots of Arc'teryx whores on this thread.. me too, and my Stinger shell has the teensiest pockets in ski-dom. Still, I rarely ski with a pack at any resort here in the East. It just looks too pretentious. "Look at me, the BC skier, braving the wilds of Okemo!"
Out West, if the mountain has significant hike-to/side-country terrain then someplace to lash my skis and store water and emergency chocolate bars is essential. I like the look of that 11L Dakine posted by ecimmortal, much slimmer than my EMS daypack. I may grab one of those for my Taos trip in March (providing they get some more SNOW).