1.) They hide my unsightly winter feet. Seriously, the clompers are hideous. There is work to be done.
2.) Socks keep my feet warmer and drier than no socks.
3.) Wearing them inside (sans shoes) typically keeps both my feet and my floors cleaner.
4.) They provide an odor barrier between foot and shoe.
5.) In a pinch, a pair of tall socks can quickly be converted to makeshift legwarmers.