Usability improvements: choose the source View & display to use

It is a good idea but a bit complicated to implement.
Feel free to post a patch if you are able to make it happens.

@hixster, if you're looking for code examples, someone wants to do something similar for Content Menu in #1583818: Support for existing views, so I suspect you'll be able to borrow some code from the patch there.

I have thought about this in D8, but wasn't sure if it was something worth solving.

At a basic level, you could make the case that only term based Views should show. However, there are definitely ways of doing other kinds of views still using the TID argument to show what you want (I've done it) on these pages. If we restrict that, it would not be possible.

You could also limit the display types to be of only Page or Block - but you may be cutting out a lot of contrib module plugins without knowing it.

Another way to approach it would be to have a simple config screen that lets the user decide what they want to show, but that is contingent upon correctly reading from all possible View types and plugins, so we are not hiding anything from the user.

In the interim, I think one way to enhance the UX is to improve the option labels for displays. Currently it is something like Display Name (plugin type), I think the ID should also be added so you can discern between multiple displays in the same view of the same type.

I've given some more thought here, and duaelFr is right. Putting in another option to limit View options and display options is more code to maintain, and a different UX issue altogether. Also, given the myriad of ways Views can be configured, I would rather leave it open to using whatever you want to use, and let the burden be on the dev/site builder to use the right View for the job instead of striking it from the option list outright.

For now, I think the form is usable, though there could be better enhancements made for usability. Feel free to open issues in that area.