It looks like Tailor is moving the header and background colour properties from the default WordPress customizer position into the Tailor menu.

I don't think this should be done for a number of reasons.

1. It means that the settings are not where users expect them (it took me about 10 minutes of searching to find it)
2. It breaks plugins that hook into the colours panel - including my own plugin, Styleguide - https://wordpress.org/plugins/styleguide/ - and I'm sure there are more
3. It's not actually a Tailor setting, it's a WordPress setting.

I can see the appeal of having the all of the colours kept together, but I don't think it's logical/ expected - but the biggest argument against is that it can break plugins.