in my experience most people don't even know what a kernel is. Also the tendency towards multipurpose is quite big. We want to do as much as possible with our systems.
Unless we're going for specialized devices space is not our problem.
Software expands to fill the available memory
source cr.yp.to/bib/1995/wirth.pdf this is an observable trend.
Unless we limit the space/computation power there is no need for us to use such things.
Now we get to IoT where microkernels are more often used RIOT OS for example is the one we use in one of our projects. But you need someone specialized who actually understands what she/he is doing to really get something working out of it.
Routers are another example.
So long story short, for microkernels to work people would need to know that they actually need/want beforehand. This would require a prior deeper understanding.
One way to compensate this is just overhype them gg go to facebook/google explain why your VKernel is so much better. Publish some Mathematical prove that less code eq less possible errors. And give the apple/microsoft speech about why this is the best kernel that you ever produced ....
in other words omit the facts, generalize, stay vague and spin a good narrative ;D maybe microkernels will become more popular ;D ...