I think it’s a good idea to take an extra pair of socks in case your feet get wet, from shoes/boots getting soaked through, landing in a big icy puddle or worse, having water/slush/snow get down into your shoes/boots, or even from sweat. I’ve been grateful a number of times that I had brought spare socks and could put on dry ones. Living in Suburbia, I’ve also used hand blowers in mens’ restrooms to warm up and dry out wet boots while in the middle of a ride.
Actually, in the winter, one thing that I put in my trunk pack or backpack and just leave there all winter unless I need it and use its contents is a Ziplock with a pair of socks, pair of gloves, hat, and a couple of chemical handwarmer packs. Saved me more than one time from a cold wet miserable rest of a ride.