We only need 'dress clothes' once or twice a year AT MOST (and usually not even that often). So we don't necessarily have something to wear when we do have to go to a dressy occasion. Sure, I could buy a dress that I'm going to wear to a Saturday afternoon wedding this July, but that doesn't mean that it would possibly work for a funeral in January given the different type of event and the vast differences in the weather here at different times of the year. And we won't mention the fact that something I bought to wear to that July wedding last year might not fit my ever changing body size by next June when I might need it again

.
I do have some slacks that I could wear for a dressier occasion, but for me the bigger issue for dressing up is shoes. I usually wear sneakers, and for dress up occasions, the shoes are the main monkey wrench in the plans. One can't really wear dress up shoes in snow/ice in the winter here (unless you wear your boots and change when you get inside the venue, but who wants to be carrying their big boots around at a wedding?). Likewise, the coat. I wear a Parka in the winter, and it looks pretty bad to be wearing that when you enter a wedding.

But I'm not going to go out and buy a new coat to match my dress.
So yeah, for people who don't get dressed up often it IS a big complicated problem.