Hello, this might be a Yes or No needed update/option choice in a theme.
Current grey monotone design of social icons in the top header is great. However many users may like the option to change that, or potential buyers may decide on whether buy this theme or not if the social icons can be shown at least in one other style design, mainly give them their original brand colours, keep size and behavior the same, but add color to these icons.
2 main reason:
1. copyright license issue – those companies like Twitter and Facebook etc may want you to show these icons in their proper brand colour
2. may benefit certain website designs which want to use more colour and highlight social icons more
i think many people are put of idea of building up their own header just so social icons appears colourful and stay content with current design, given at least another option on how to show icons may win more customers and be a valuable time saver for those who want to customise theme that one extra step.