Now it seems Microsoft has removed colored icons in latest build 10565, And Gabriel Aul, head of Windows Insiders program has tweeted and explain that coloured icons were part of an A/B test and it will be coming in future builds if Insiders want it.
@LizardRumsfeld They were an A/B test, some got color and some not. Still evaluating data to see where preference landed I think.
— Gabriel Aul (@GabeAul) October 16, 2015
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