[rizzin]

I assume the goal is consistency in spelling. Choosing American over British is probably just personal preference.

[yen223]

Most code use American English anyway (e.g. "background-color" in CSS), so it's usually a good idea to standardize around it.

[richrichardsson]

I cannot write Americanised versions of words without incredibly concious thought about doing so, which breaks my train of thought. I find it easy to understand what is meant by color, why shouldn't our cousins over the Pond be able to understand what a colour is? (stupid example, but you get the point)