WARNING: Old Guy Jacket Rant.
I am constantly amazed at the number of people day skiing at areas with backpacks on. What that heck are they lugging around all day? If you have a couple kids and need to keep them supplied it's one thing, but a pack is really a hassle on chairs or a tram. IMO if your jacket cannot handle your needs for a day of skiing inbounds then it is not the right one.
A good shell with a powder skirt (removable if you like), pit zippers, arm pocket for electronic tickets, comfortable collar the right size to seal with a neck gator, and ample pockets inside and out. It should be big enough to layer with thick warm clothes underneath when necessary. And lose the belted low pants. High waisted pants (my favorite are very low bibs) mated with a powder skirt keeps you wind and snow proof unless you are cartwheeling in deep snow. There are tons of high quality jackets in the $200 or less range that will make you a weather-proof mobile skiing unit. Get a good jacket, lose the baggage, and point'm down!
I bought a pair of Flylow Baker bibs this season. Amazing how that little bib virtually eliminates drafts around the mid-section, making them feel much warmer. The Bakers are shells, and I bought some primaloft belay pants to wear underneath on brutally cold days. The other option would be to spring for insulated bibs, but Flylow doesn't make any, and as others have mentioned, built-in insulation reduces the versatility of the piece in question.
Shells have their place, as do insulator layers; micro-puffs, etc. Insulated jackets and pants might not be as versatile as shells, but for really cold, lift-served days, say below 15F, I'm not as concerned with versatility as I am not freezing my ass off.