It's simple. To anybody who appreciates the pragmatic of "what works", suits look silly.
Let's break a suit down:
jacket: why? are you cold? there are better garments, made of better material that can keep you warm in a variety of colder than comfortable climates.
vest (optional): why? it makes you look like a poker dealer, but you forgot your green rimmed sunshade.
tie: supposedly to add some color, but looks like a noose, or a lead rope used to guide livestock around (the signal I always get from a tie), may as well just wear a shirt with some color. Predecessors to the tie are generally regarded as silly looking today. Nobody takes an ascot seriously today, bolos look ridiculous, bow ties instantly turn somebody into a fussy professor, and nobody would be caught dead these days in a cravat http://upload.wikimedia.org/wikipedia/commons/7/71/Louis1667...
oxford or similar shirt: oh where to start....buttons, from a time when fabrics couldn't be manufactured with the properties of jersey. Collar, to catch sweat from...all the sweating you're doing from the 3 layers of unnecessary clothing you're wearing. Sleeves, long to be proper, even if it's hot, buttons on the end, because again another vestigial holdover from primitive fabrics, or french cuffs, because who doesn't like to assemble their sleeves when they get dressed? Oh, and it has to be tucked in, leading to constant retucks throughout the day, or embarrassing shirt stays clipped to your socks or looped under your feet looking like some kind of lingerie reject.
Toss out that mess and we're left with ridiculous, overly expensive uncomfortable shoes that need constant maintenance, black socks and what are essentially just expensive slacks.
(edit: I'm frequently caught wearing suits for various work reasons, and I feel like an idiot every time I "suit up")