I'm all about hating on the psychiatry profession, but I believe what may be missing here is that these diagnoses are always optional.

If you like your grief, you can keep your grief. But if you need help, the criteria need to be there for you, for insurance companies, employers, and such to systematically do all their accounting and such.

It's a bit similar to a lot of controversies around the autism spectrum. If it's just a personality quirk and you're a functional adult then it doesn't really matter if you meet the this or that criteria. If you like your autism, you can keep your autism.