And what is the point of FF mirrorless? It's compact and lightweight?
Just because mirrorless starts in the p&s region doesn't mean it's only good for holiday snaps!
The main advantage of mirrorless next to the missing mirror (= smaller design) is that the sensor can see the picture all the time, so you can have lots of information previously missing in the evf - like focus peaking, zebras or numerous other electronic hints.
With a good sensor (ff), a good electonic viewfinder and the appropriate software pro mirrorless will make the current dslr designs look like they are from the stone age, "with mirror" will become a nice market in 10 years from now. Why do you think Canon invested so heavily in their dual pixel sensor tech?
That seems about right. Not only do EVFs give you useful information, without moving your eye from the viewfinder you can see the effects of changing exposure compensation by turning a dial while looking through it (that's true, at least, for my Olympus EM-5), which makes getting exposure exactly right much easier. Accurate focusing is easier too - no need for microadjustments to align your lens to your camera.
If "compact and lightweight" matter, you're better off with a M43 camera; in addition to the mirrorless advantages mentioned above, the smaller sensor allows smaller, lighter lenses - *that*'s where the main size/weight advantage comes in, not the fact that they're mirrorless. I may be wrong about this, but except for how it physically connects, the size a lens for a FF camera has to be has little if anything to do with whether there's a mirror in the camera body; and if you're going to lug around a 70-200 f/2.8 FF lens, it doesn't make much difference how big the body is (except that ergonomically a bigger body works better).
If Canon were to make a mirrorless EVF FF camera much the same size and shape as my 5DIII or 6D, with built-in image stabilization at good as that provided by the top end Olympus bodies, I would be delighted. But I would also be delighted if sensor technology developed in such a way that m43 sensors became as good as a current FF sensor; the gap keeps shrinking as it is. I wonder which will happen first.... Interesting times, either way.