I am not entirely sure I would agree with this, or maybe I just don't understand your logic. As a photojournalist (which I am not), wouldn't you want more reach/range than something with just 12mm from front to back? I agree with your f2.8 assessment, it wouldn't be needed for landscape, more for low-light indoor shooting. However, wouldn't you want to use a lens with this FL for landscape too?
I think I'm trying to say, a FL like that would be useful to take pictures of a crowd you're standing in, not one you can step back from. I think PJs find themselves "in the action" a lot- thus the wide FL necessary because they can't (or often- don't want to) get away from the action for a wider angle. Also things like nightclubs, etc. where you're trying to shoot people literally a couple feet away from you.
The fact that these wide FLs are also useful for landscapes doesn't mean there can't be different lenses designed for different purposes within this category. The 14-24 (and this new 16-28) sacrifice filters in trade for that bulbous front element, allowing a faster aperture. Something like the Nikon 16-35, they give up some of the wide aperture in trade for a smaller lens- and a design that allows a screw-on filter. I think Nikon put VR on in order to enhance the utility of the lens, giving it a little more ability in marginal light when used handheld.
If you use gels, the lack of a thread really doesn't matter, and you don't have to worry about vignetting with thicker filters too.
Not sure I know exactly what gels are (are you referring to rectangular drop-in filters?) but how would you affix it to the front of the lens if there is no thread? Unless you handhold, most gels need a screw-on filter holder in order to accommodate the gels? Lee had to make a custom mount just for the 14-24 because it lacks filter threads.