I'd really hoped for the 16-50/4 IS ...
I will love to have a 16-50 f/4 IS too. But I don't think that's coming. It is probably a figment of someone's imagination. Sigh
While I can understand the desire on a 1.6x crop. I really can'y see any benefit of an IS unit on a full frame 16mm lens. If you need stability....then use a tripod. Should anyone really be hand holding less than 1/15th sec? If the shot is that important....put it on a pod, end of story.
Not everyone wants to hike with a tripod. I do a lot of forest hikes where I go minimalistic on the equipment. Forest environments were tailored for UWA lenses. Having IS would be great.
Yes, and even if you can bring a tripod: if IS can do the job why not use it? It is both technology to help the photographer. I don't always know what position I get in and I don't want to carry a tripod all the time (IS is a lot easier).
Futhermore: IS is handy for (quick) 'creative' stills and video in general. Not all people want it but to say: "put it on a pod, end of story" ... no ...