Hmmm.....What am I missing? Since most of the discussion here centers on landscape photography and DR, why not bracket the exposures and use a restrained HDR approach, or even combine the shots manually in Photoshop to optimize detail? Granted this would not work perfectly in every situation (windy conditions -- waving plants, or at the coast with moving waves or wildlife in motion), but it might help to level the playing field. Also, suppressing noise in the shadows with a Photoshop plug-in should help, too. Admittedly an extra step, but better than spending $2400 plus purchasing an unreliable adaptor. Just sayin'.............
For almost 2 years I have used "restrained HDR approach" with my 5D MK III and I like it very much. However for those who are not interested in HDR (even if it is "restrained") there are several benefits to having a Sony a7R1.
Superior image quality for landscapes2.
Generally landscape photographers tend to travel quite a bit, so they will appreciate the light weight3.
You can use superior optics from Canon or Nikon e.g. Canon EF 14mm f/2.8 prime lens or the Nikon 14-24 f/2.8 lens.4.
It makes for a great back-up body
Considering its strengths, $2300 is a reasonable amount of money (if one can afford it) for the a7R.
Finally, it seems to me that your comment about "unreliable adapter" is based on what you read online, instead of actually having used it ... in addition to owning the Metabones adapter, I have met 8 people (in Australia, Singapore & the Middle East) that own the Metabones adapter (3 Nikon & 5 Canon versions) and all of them are very happy with their excellently performing Metabones adapters ... all products including the most expensive Canon/Nikon lenses will have variation from copy to copy, yes there will be some that will have a problem, but that does not stop people from buying them.
Obviously it is not for everyone ... for photographers who already have some excellent UWA lenses and want to get even better results than their current camera and they can spare/afford $2300+$350 (Camera+adapter), then this is a fantastic camera for landscape.