Publishing yet-unpublished works is another example that this is only a step out two away from.
IMHO it's not at all strange for the family (particularly the offspring) of the deceased to make decisions, including creative/artistic/editorial decisions, about how their loved one's work and life are used and portrayed.
He chose them because they were the ones most compatible with the other published works, because his father could never revise them. (Unlike The Hobbit, which as revised to make it more compatible with upcoming The Lord of the Rings.)
He was specifically chosen for the job by his father, who may not have agreed with the choices but was unequivocal that Christopher was the one to make them. Christopher himself has said that he'd change some decisions if he were to make them again, but that's true for any author.
To me, I'd just as soon The Silmarillion bear Chrisopher's name. Not as a matter of honor, but as a matter of clarity to fans who want to know what's "really" Tolkien.
I suppose our wills now will need to include statements about not allowing family/etc to do things like this, at least under our names.