Why are you using a tele for landscape? I generally use my 24mm 2.8 (ancient manual Sigma) for landscape, and I've had my eye on a 15mm prime for a bit too. For landscape you want wide (or ultra wide), for models you want tele, for street shooting you want "normal" (40-50mm, though I prefer 24-28mm for this too).
Fringing depends on the lens, not how large the aperture is. Worst case, you have to stop the 1.4 down to 2.8, to clean up the picture and regulate CA, and generally a fast lens hits the sweat-spot before the largest aperture of a comparable slower lens. Faster also give you more options, and more versatility. I might never want to go to 1.4, but its there just in case.
I agree with your sentiment though. Speed isn't the be-all-end all, the quality of the glass is. I'm a Pentax shooter, and they have two (three now) recent 50's, a 1.4 and a 1.7. I own the slower lens, and had to hunt for it a bit since it takes pictures I find more aesthetic than the 1.4 (better contrast, renders a bit warmer, sharp wide open, where the 1.4 needs to be stopped down a bit). And old Leica 50mm 2.0, or a Zeiss Jenna 2.8 will probably take better pictures, and have better glass, than my 1.7 or the 1.4. Sadly the Leica and the Zeiss cost 10x what I paid for my lens. Some lenses are almost mythic in their quality, seek these out instead of hunting for mere numbers.
Lens porn aside, you want to compare actual images (RAWs if you can find them), and read both subjective and objective reviews.