I will always maintain a position of helmet use being a personal choice. However some things to be considered about the reasons some have for not wearing them.
Uncomfortable: If the OP's helmet is 12 years old, the rate that tech moves these days that is ancient. Helmets are like boots, people can recommend models till they are blue in the face, YOU HAVE TO TRY THEM ON! And I don't mean just 1 or 2 that some random dude on the internet recommended. I tried on 15 before I bought mine (Giro G9) with the amount of manufacturers and models available you will find something that fits right.
I don't ride park: In my experience, outside the park, most concussions happen on easy groomers. These areas are congested with inexperienced riders/skiers, sure you can control what YOU do but shit does indeed happen. I also seem to edge catch more on green runs, when I'm riding more advanced runs I'm 110% focused on what I am doing and the terrain directly in front of me. On green groomers I'm picking my line based on the people in front of me and not so much on what I am sliding over.
Not warm: *I have no idea about the beanie/fit thing* I usually have to open vents to keep from sweating like a pig in mine, maybe cheap helmets don't have as good of insulation
The only time I can remember not venting mine was a heavy snow at Keystone a few years ago, was probably in the teens, and dumping. Still warm enough, I can't imagine riding in weather that was much worse.
Doesn't look cool: If you are going to the mountain just to make a fashion statement, then why bother riding at all, just gear up in a grand worth of Burton crap and hang out in the lodge. If you are THAT worried about what other people think, it's an issue with your self esteem....besides mine looks bad assed
All in all, as I have said in these threads before, better to have it and not need it, then need it and not have it...your squash your choice.