PB PM said:
I can see an F2.8 wide angel lens being good for closeups indoors, and subject isolation.
That explains the wide aperture need.
Just a note about this. I found that if you are far from your subject with a wide angle, it's better to shoot with a small aperture to have everything in focus because having only part of your image in focus and rest just slightly out of focus (because your DOF isn't short enough) gives a less interesting image than if everything was in focus... However, most of time when I shoot wide I want to be close to my subject and what to isolate it.. that's why I like the 11-16 f/2.8 but I want more. I wish I had a 24mm f/1.4 or 28 f/1.4 on full frame because what you can do with these is simply awesome.. I love my 20mm f/1.8.
http://farm3.static.flickr.com/2469/3812805733_b65fabe542_o.jpg
I couldn't make this with a small aperture and shooting this with a telephoto would kill all the sillyness.. off topic but, do you think I needed just a bit more DOF in that pic? I'm a bit unsatisfied.. maybe just a tiny more DOF for the lips and nose) I kinda like that weird bokey from the 20 f/1.8
Back on topic. For someone who shoots landscape in daylight, a wide aperture is useless... but I never ever shot a single landscape photo... I use my wide lenses indoors or outside at night so right off the bat the wide aperture helps with the light because I don't carry a tripod around. I'm also a maniac of short DOF combined with wide angles... my dream lens would be a 12-28 f/1.4 AF-S for FX I know I'm not realistic here but just saying.