In reply to Andreas Nurbo.

@andrea
1. the separation between admin and front end is totally artificial. When you have the admin bar you are at admin, no matter what url you look at.

2. The whole discussion comes from the need to communicate between various plugins, on the basic level have some hood system in JS which is parallel to the PHP one. If there will be such a thing on "admin" it is a no brainer that it will be applied to front end, obvious candidate the rest API.

3. OK, maybe not the greatest example, but you should follow guttenburg development.... right now the meta is JS driven, how does a user disable the display of the meta box he do not need without rebuilding the whole guttenburg project?