i don't have any microspikes, so take this for what its worth.
they are designed for conditions when full crampons aren't necessary, such as a bit of snow and ice. most hikers/walkers aren't going to need full crampons and these are lighter and more flexible. they can be worn with trail running shoes, or just about any shoe. i think a lot of trail runners use them in the winter. since they slip on and off much easier than crampons, people use them in everyday life as well.
I have a friend that wore some on a recent trip where there was some snow and ice on the trails and he liked them. he said he didn't really notice wearing them. he was wearing some trail running shoes.