The main issue is that it makes the component harder to reproduce without using the template. `primary-thumbnail` also implies that there can be other thumbnails, which we don't really refer to but also makes it harder to wrap your head around what a list item is.

Just calling it `oae-listitem-thumbnail` would be more understandable, and special styling can be applied to the first occurrence, but I guess that's pretty much the same as what was there before as well.

My understanding is that the container is not really necessary, in which case my preference would still be to go back to the previous approach.