Not really because on a wide angle you can shoot fine without IS at 1/30 or possibly even 1/20. The only reason you want IS on a wide angle is video, to help stabilise handheld video. And I assume this is the reason Canon introduced these lenses.
When shooting a stationary subject at 1/30 or 1/20 in the evening/at night you're using a rather high ISO value. Thanks to IS you could get away with a lower ISO value which means less noise. And that is always a good thing. 
The point remains, with Nikon's dynamic range and wide angles, Nikon is really the obvious choice for landscape shooters.
True, but there are also many great landscape pictures taken with Canon cameras, so it doesn't mean people should never use Canon cameras for landscapes. It just takes more effort/workarounds because of the limited amount of DR at low ISO.
Ergonomics is a big deal for some. I do like Canon ergonomics but, that can only go so far. I've grown accustomed to Nikon's layout that it has become second nature. I can still pick up a Canon and figure out the basic controls (M mode, ISO, SS, etc.).

Well, with ergonomics I don't mean the layout of the buttons or the menu. I could also get used to that. I really mean the shape of the camera. My hands don't like it. 




