I ski mostly backcountry off 542, but still find a season's ticket worthwhile because:
1. It snows a lot. On bad visibility days, trees, known runs, and other tracks are nice. There are a few bc tree skiing areas around the ski area (Austin Trees, Herman Saddle), but most of the tree skiing is in area.
2. It snows a lot. On many days, the snow is just too unstable in the backcounrty to ski anything over 30 degrees, and some days you have to pole down 30 degree slopes. But these are not days to be missed!! Ski the area until things calm down.
3. It snows a lot. Unless you are up there every day, you will likrly see fresh snow and will need to know how well it is holding on to the underlayments on the various aspects and angles. We usually do a few runs in area, testing short, steep "test plots" to get some idea of what the sluff situation is. Then we will try a bit of lift served back-country (the Elbow, the Elf Chutes, The Hemis, The Arm to test on known conditions what we are suspecting. Then its off to the untracked goods.
4. It snows a lot. And it rains some, too. A season's pass gives you the opportunity to say "screw it" after a run or two on truely horrendous days without having to have wasted the price of a ticket. Plus, no waiting around at the ticket window in the morning on powder days.
5. Even on days where you are headed for the back country, a lift assist can save a half hour approach to Ptarmigan Ridge, Lake Anne etc. More if you are lugging in a pack for an overnighter.
6. ... and the final argument for a pass: The Arm!!