Do pots need blankets? No. Do plants feel more comfy and secure to be surrounded by nice cloth, like humans do? Also no. But here's the truth behind these: sometimes the plants that you get from inexpensive stores can come in some really awful pots, and you don't always have something else to put them in on hand. So, now your plants can look cute placed in something that's aesthetic no matter what pot you get them in!
To top it off, this cozy protects any delicate surfaces you'd like to put your plants on from the rough undersides of rough pots!