They were proposed here as an alternative to domain-restricted sub-CAs, but GP and me have given counterexamples as to why they're not (or at least not without downsides).

> No one is saying wildcard certificates should be mandatory.

Nor am I saying they shouldn't ever be used.

You may interpret it differently, but to me:

> Why? As I understand it, the domain owner can assign the name you “trust” to any server already. Might as well trust all names by that domain owner.

Essentially means "default to a wildcard." My example is absolutely a good reason why you should not default to a wildcard. There are situations where they make good sense. I use them myself. It's a terrible idea to use them everywhere and always, which is usually what ends up happening when wildcard certs are the default approach.