I've already mentioned a huge heap of reasons why IBIS is a bad idea.
IBIS, meanwhile:
- can actually cost you IQ (so can OIS), if used inproperly
- will make your camera more expensive and bigger
- will be another thing that can break in your camera and will make it more complex and less reliable
- cannot actually be switched off (if its set to "off", it just holds the sensor actively in place, but its still active and wastes current)
Obviously I'm not Derrel, but some of the points you mentioned,
I disagree with.
- can actually cost you IQ (so can OIS), if used inproperly - So can choosing the wrong shutter speed, choosing the wrong ISO, choosing the wrong aperture, choosing the wrong white balance, choosing the wrong focus point. Any tool can be used
wrong, look at all those people that use the side of an adjustable wrench as a hammer (and I don't mean the kind where manufacturers gave up and integrated a hammerhead!) and get lousy results.
- will make your camera more expensive and bigger - Don't the fairly tiny Pansonic Micro 4/3 cameras have IBIS? Fujifilm has one for under $1000, and Sony's A6500 is both small and relatively inexpensive too.
- will be another thing that can break in your camera and will make it more complex and less reliable - Perhaps, but when I search the Internet for people commenting that their IBIS broke, it doesn't look like it's a particularly widespread phenomenon. As for complexity in general, having just examined my old EOS Rebel K2 film camera yesterday, I'm not sure that a lack of complexity is really a good thing.
- cannot actually be switched off (if its set to "off", it just holds the sensor actively in place, but its still active and wastes current) - My assumption is that depending on the power options one chooses, already a requirement for mirrorless cameras anyway, IBIS will shut off and let the sensor go limp or to its parking position when the camera isn't otherwise ready to take pictures. After all, camera manufacturers are already painfully aware that their mirrorless cameras have much shorter battery lives, they have every incentive to attempt to curtail that. On top of that, all these lovely people that review cameras are happy to publish all the runtime performance information they collect, you can find out about how long the camera will go on a given charge of the battery and decide before you buy it if that's right for you.