I agree. It all depends on what I am shooting and WHY. Sometimes there is a shot you have to get no matter what. Sometimes it is low light and you really have to crank up the ISO and get the noise up higher than you want to get the shot. You need it you shoot it. I think using my 11-16 in the DX mode follows the same rules. The 24-120 will fill most of my wide angle needs but there are a couple of places I go that I need the extra wide of the 11-16 so I may forgo the IQ of the corners to get the shot I have to have or at least till I can afford a true Full Frame wide angle lens. Any one know of a really good deal on a wide angle prime for FX? Don't really need the zoom or even auto focus. I have found that even with the 11-16 I just set it just on the short side of infinity and shoot away and it is always in great focus as long as I am at least at lest 6 or 8 feet away from the subject.
The 14mm Rokinon is a pretty good lens. It's manual focus but it can tie you over until you save up for a shiny expensive one.