Ronny, I also assumed that that it just doesn't have the same punch as Loxias. It's difficult to match Loxia 21 & 50 (& 35 and 85) on landscapes. Few months ago I was afraid you getting this zoom that it may not get results you are familiar with other lenses.
Phillip's 16-35 looks plenty sharp on forum size, thou lacking same kind of punch what Loxia 21 images have.
I have already 3 times decided to not buy Loxia 21, and I'm again considering it...Then again realizing that I never would shoot landscapes with so wide lens, and having better lenses for 21mm boke shooting, and then not considering buying it anymore...
Samuli