I think a common analogy is that this is a bit like the sonic boom when something travels faster than sound in that medium.
Similarily I don't see how it explains the glow. Photons get generated regardless of whether they pile up or not. It's a consequence of particles bumping into atoms not the whatever speed of light might be in this medium.
How is piling up important?
For a slower than light particle, you also get emission, but it is completely random and thus does not give the well defined emission in a cone of Cherenkov radiation.
For a faster than light particle, the spherical suddenly line up to form a cone:
https://en.wikipedia.org/wiki/Cherenkov_radiation#/media/Fil...