I disagree. To say that I.S is over rated and bordering gimmicky is a total disregard for systems who have thrived on it and the countless dollar bills invested on the technology. Regardless of whether the stabilization is in lens or built into the body, in a professional telephoto lens or a high end binoculars and even your average consumer zoom. It's difficult to think that it's all simply a marketing ploy, and that 'since everybody does it my camera should have it as well'. Although to your defense, with regards to video feature in DSLRs that is quite the truth. But proper implementation of video (manual controls/ bitrate and codec) do make other DSLRs stand out from the rest and are certainly not gimmicks but actual professional tools.
I would like to address some of your points your brought up and I hope you will take no offense, what I've learned is from others and we are all learning to the grave.
No matter how small a movement there is, if it isn't on a stable platform, the sharpness of an image will dramatically decline. This is why I.S is It is the 'lazy man's tripod'. It is true, IS can never beat a tripod. Any picture taken with a tripod will be sharper hands down. In fact every photographer who even consider themselves to be a serious enthusiast should love the tripod, the image difference is very much perceivable to any human eye. And to take your point on fast shutter speeds, in the eyes of any camera regardless of it's shutter speed, our hands are the equivalent of stage 3 parkinson's disease. It is just not as noticeable at a faster shutter speed, but it doesn't mean the issue is completely elevated.
Why trade I.S on the pretense that ISO performance is 'fantastic'? I think this is where your argument starts to question itself. I think it is not quite wrong to say that any picture taken with as little electronic manipulation generates a better picture. That said I would never trade ISO performance for IS. ISO performance no matter how fantastic will always compromise sharpness, detail and dynamic range for proper exposure and should not be an excuse for anything other than 'I did not bring my flash'. (Not that this does not include electronic image stabilization, which is mainly used in consumer digicams or in Olympus E-Ps during video mode)
Using IS does not mean you will be able to capture any moment but if people have shot moments in 1/25 or 1/15 even so if anything, IS only serves to aid those times when you have to shoot at that. The most popular example I can think of are concerts.
Sure, if the shutter speed is too low you won't be able to capture certain types of photography e.g. sports, but photographers who shoot concerts, fire jugglers or dances tend to purposely use a slower shutter effect to capture the movement as well. I think this is one of the times when IS, really is useful then. Since you would be trying to capture the movement of the subject, not your hands.
It is a- better to have it than not feature, but I agree as well that it is also a 'can live without it' option too.