The sleeves of a dress or other garment can change it completely. People will obviously choose certain sleeves or practical reasons, but they can also have a strong effect on the way that a garment looks.
Buying a certain dress might not even be an option for some people if the sleeves are too long or too short for the weather in question. They might decide to purchase the dress or shirt and have it modified. However, a lot of other people will just find it easier to look for something else that is otherwise similar. There are only so many sleeve types, which should make the selection process a bit easier.
People might not think that something as simple as a few inches of fabric will make much of a difference regarding temperature, even though their own experiences might suggest otherwise. However, even sleeves made from fairly light fabric can retain heat very effectively.
Rolling up some sleeves might be relatively difficult. The dress might also look completely different if the sleeves have been rolled up, and some people might be reluctant to make that change as a result. Sometimes, it can make more sense to get a dress or shirt with almost any sleeve type, and purchase something to wear over it. An outfit can look like it’s been very carefully planned if that is the case.
If people are worried about facing unexpected cool temperatures, bringing along a nice jacket can help. Lots of dresses are designed to have these sorts of additions in the first place, which should make the process of choosing a dress a lot easier for people who are worried about facing unexpected changes in the temperature levels. They should still avoid assuming that the sleeves won’t matter.