"If we accept for the moment that 90+% of the cream legbars in the USA are colored cream legbars, then the logical deduction is that the silvered cream legbar is really a minor variant of the predominant strain. Once you have made these deductions, then the question is begged why would the Cream Legbar Club and some individuals push so heavily in favor of a minor strain?"
The logical deduction is not as you describe, necessarily; it is possible that some number of early US owners were in such a hurry to populate that they bred everything they had without reading the British Standard or researching what was commonly accepted as correct according to that standard - or - they actually selected those with more color in early matings and thus set forth the explosion in population of more colored birds by percentage.
In my opinion the Standard as written is in need only of minor tweaking. I do think it logical to add something to the effect minor shafting in females is permissible, but if it isn't in there, it isn't.
Correct color is important to the Standard, indeed, so we are able to select for it after we have selected for vigor, type, and fertility. Type - what makes this bird a Cream Legbar, includes crest, blue eggs, and autosexing, as Walt patiently reminds us. When you hatch chicks you can't sex at once, you risk losing the autosexing trait of the breed if you repeat that breeding or go forward with the get.
My position is not based on what I have, as I have only a young (4 months old) trio that are all undersized IMO and the male has some chestnut, but they do have other characteristics I like, and I also have a very young (4 weeks) pullet growing up with the broodies right now, no idea what she will look like in a few months' time.