Quote:
Originally Posted by
mack11211 
Yeah, it's simple.
Pleats came in early in the 20 c after a fashion for wide leg trousers arose. The engineering issue was how to draw that fabric in at the waist. You can dart it or pleat it.
When the drape look came into fashion in the 30s, pleated pants allowed a leg that was narrow at the waist, wide at the thigh, and tapering slightly to the ankle. The pants were often held up with braces. This is how men wear pants in all the movies of the period.
Pants were worn not at the hips but at the natural waist, which is the narrowest part of the body. Spoo is well turned out but note that his pants waist is lower, in the standard contemporary style where pleats have less of a point. He is still very well turned out, of course.
Whether you wear pleats or not, assuming all choice are available to you, depends on the line of leg you want to create given your bodily materials. Are your legs thick or thin? Is your waist large or small in relation to the rest of you? Is your butt big or small? All of this goes into determining the line of leg you want, given that dress trousers should fall easily and effortlessly rather than strain and reveal the family goods as jeans do.
I am afraid that you are wrong. Pleated pants date at least from the 1840s.
My remarks in Ask Andy three years ago:
"I recall that in the classic movie Camille (1937)
with Greta Garbo, which is set in Paris in the 1830s
or 1840s, Robert Taylor, her co-star is shown
in trousers with multiple pleats. I assume
the Hollywood costume people knew what they were
doing."
http://i111.photobucket.com/albums/n135/pinkyjune/25.jpg