Suade...
The adjective colourful/colorful can have two connotations. It can be complimentary or derogatory/insulting.
In the latter case, some synonyms include: dramatic, expressive, unrealistic, unusual, flaky.
So when President Obama described Duerte as colorful, he may have meant either or both connotations, and he left it up to the listener to decide which connotation he may have meant.
Great example Suade...
Sudeep...
Who knows? Who knows why the Americans changed the original spelling?
My best guess, as more easily seen with other changes such as recognise to recognize and analyse to analyze, is that the American spellings attempted to be more phonetic.
Personally, if I were to spell the word phonetically, I would spell it as "culler" since that's the way it sounds in North America :)
Thank you @Richard for some colorful idioms:) I hope it will make the sentence more colorful.
BTW, Richard, What is the mystery between not using "U" in American "Color"? Do you think by not using U in "colour" makes the "colour" less "colorful" !:) I'm sorry for this stupid question:)