In reply to Gary Bairead.

When you’re saying “easier for users” you mean “easier for advanced users”.

I mean the exact opposite. This will make it easier for novice users who might be provided with a css snippet to tweak something, like hiding part of the entry meta. It'll makes it easier for volunteers in the WP.org forums to help users with css tweaks too.

An advanced user who wants to add more css can use a child theme if they want to.

The reason for mentioning WP.com, JetPack, and themes with a custom css option, is because you appear to suggest that there's only a demand from 0.4% of all WordPress sites. That isn't accurate. It's difficult to gauge how many sites would use a feature like this.

One of original purposes of the customizer was to allow users to preview real-time changes to the appearance of their site. Adding the ability to do that for css tweaks seems like it could potentially help a lot of people.