I am strongly in favor of this sort of “mode switch”. It is different than but still I think quite similar in concept to this idea I had some time ago for how to make writing in block-based editors smoother:
Quite simply stated, the reality is that in most tools we spend far more of our time creating “content”/data than creating “structure” or administrating. However it is a very nice thing to have editing capabilities easily and quickly accessible. A great example of this is the drag handles on Entity views. Sometimes I am using an Entity view, have no intention of editing it, but suddenly realize I’ve had some friction using a particular field for a while now, and I want it to be in a different position, or have a different name, etc. In these times, the ability to edit the Field config immediately, on the Entity layout is fantastic. But 99% of the time I don’t need that, so the drag handles are distracting, and even occasionally result in an accidental (though usually easily correctable) repositioning of a field. As I have discussed elsewhere, they also mess up the tab order (still not fixed 
).
This seems like a small problem, and in many respects it is. But it’s also one of those things that contributes to the Fibery interface being more “heavy” and perhaps intimidating for some new users. And, as I mentioned, it subtly but very definitely gets in the way/distracts/etc. for me as a well-versed admin user too.
Long story short, I agree there should be admin vs. non-admin mode for a given user (if they have appropriate permissions of course). This could be a simple toggle on the workspace dropdown in the left-hand menu, to make it global, or on individual Views perhaps, though I think the global toggle is probably best. And I think it should remove e.g. Configure App and Create New View buttons, as well as remove Entity rearrangement controls. That said I would also like a simple modifier key to bring at least some of that back very quickly. See above the linked post about the usability enhancement for block-based editors (there I propose holding down the Alt key to temporarily enable admin-type, e.g. layout, modifications).