I wanted to start this post by writing; "if you want ultimate utility clothing, you want a trench" and then I thought I'd better read the exact definition of the word utility just to be sure:
useful, especially through being able to perform several functions; and
functional rather than attractive. E.g. "utility clothing"
"Funtional rather than attractive" is definitely not the case (although that did make me LOL) but I think the trench coat can definitely "perform several functions" clothing wise and therefore feel that the word "Utility" is still appropriate.
My dad has worn a trench for as long as I can remember, to me it was always something that businessmen wore on their way to work. And then I discovered Burberry and realised a trench is also something that woman can wear while on their way to work. But its functionality extends far further than that - It's dressy but also casual, as appropriate for work as it is for Sunday brunch and can be layered or worn with nothing underneath a la Lara Bingle (below). And if there's any doubt about Utility Clothing, I think this post proves that it can be both functional AND attractive.
Images: Maurie and Eve, Theyallhateus, 4th and Bleeker, @brooketestoni, Google Images.