They just don’t do krewe costumes like they used to. Krewes like Proteus used to parade, then go straight to their ball (in 1899, that would have been held at the French Opera House). The maskers wore their costumes for the tableau on the floats.
In 1954, the Krewe of Venus’ theme was “Battle of Waterloo”. While the uniform isn’t quite historically accurate, it’s an awesome costume.