I think there are a few reasons for the use of the Common skill:
- It allows for starting characters to produce some much needed emergency clothing that helps against the cold (as poor quality clothing is worse). This is more a game balancing measure than a realism one when it comes to the skill used.
- It automatically blocks the production of clothing of a quality better than Decent, as the time it takes to put together UrW clothing doesn't allow for high quality products.
When the process is changed (I believe the long term plans are to revise clothing at some point), the applicable skill ought to be tailoring, i.e. a new skill, although I wouldn't mind if a new category of quickly thrown together clothing covering what characters can make today would be introduced (and which villagers would probably not be prepared to buy).
Proper tailored clothing ought to take much longer to make (requiring the ability to pause/resume the task) than the current process.