Having taken a brief intermission, I wanted to finish up the miniseries I started with On Nudity. There, I had talked about how nudity is a literary tool that can be used to show a wide range aspects of humanity. The primary thing, though, was that a naked human is purely human.
With tattoos, we find this strange middle ground between clothing and nudity. When we see a tattoo, it is still exposed flesh, and yet it isn't the same as when the bearer was born. We acknowledge tattoos as a covering, and yet they are also considered a part of the user's body.
In most stories, I find clothes function similarly to tattoos. In almost every cartoon, the characters always wear the same outfit. The outfit becomes as iconic as the face or any other physical feature (if not more so). Whenever they wear a different outfit, they look unnatural to us, like they are wearing somebody else's skin.
In the real world, people are not their outfits. Doctor's don't wear their lab coats all day, everywhere they go. White collar workers do not wear their suits and ties all the time. Similarly, you should not assume that every person in a t-shirt and shorts is a lazy bum. You will be disappointed quite often if you do so.
But in storytelling, that is not always the case. When you only ever wear one outfit, no matter where you are what you do, whether you're working or not, then that outfit is your skin.
I won't say whether it is a good thing or a bad thing, because it is neither. It's just a concept to consider. How much is your character's outfit a defining characteristic of your character?