[BoboStin]

I think it is mostly a time management issue.

Although there are different thought processes on it too. Practices are really short where I train now so people get all their gear but men on and will practice kata shortly before normal keiko. In other dojos I have visited, wearing your doh while practicing kata is a no no and it doesn't matter if it wastes time to take off or put on gear because according to them you shouldn't do that.