My four square shell has a skirt in it with three buttoned loops to tie it into my pants' belt loops. Never rides up, and keeps snow out of my ass!
Works awesome. Also does a great job at securing skins in my coat on those days where I want ot pack them in the jacket for the down.
My first jacket that had a skirt years and years ago was just a band of material with no attachments, it sucked. Those few little straps are needed to make the difference from it just interfering or actually functioning.