Via is just one of the parameters you can use to tweak the autorouter. Via add a little cost in drilling, they take up space, and other things being equal and it is better for a route to stay on the same layer.

The use of via has both advantages and disadvantages, it depends on your choice.

I wouldn't say that via is not good, sometimes can be used as good for us.

I think the reason is that vias could occupy significant space from other components, so that the size of the PCB need to be bnigger, which will cost more.

Very interesting post.