Major League Baseball Mlb Teams

Why no solid color pants in Major League Baseball?
Why don’t any of the baseball teams have solid color pants to go along with the alternate dark jerseys? Does MLB have a rule against this or is it merely a matter of aesthetics?
right now it’s style. In the past teas wore some colored pants.
Phillies and Cardinals had light blue pants as did the Royals and Brewers often for road games. Light blue is in actually allot of teams’ history as their road unis. (70′s-and into the 80′s)
The White Sox wore Navy Blue Shorts in 1976 for 3 games.
The NY Giants wore solid Black for the 1905 WS and again similar all black in 1911.
The Indians had red pants with red shirts in 1975
I am certain there are others.
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