Originally Posted by
JudicatorPrime
In the 1960s certainly no one but Thor could lift it. But in the 70s and after, Mjolnir had a fair number of other wielders. The earliest that I can remember was Red Norvell, who didn't want just Mjolnir, but also Sif. Red also used some of Thor's other paraphernalia, iirc.
It's a fairly common plot device for the hero's powers or likeness to be borrowed at some point or another. While in the myths Odin certainly never intended the hammer for anyone else -- the Asgardians had too many enemies to trust a weapon like that to anyone not of Od's blood -- Marvel folks took liberties with the myth and made the enchantment a two-for -- you get both Mjolnir and the powers of Thor.
The enchantment is the clearest form of foreshadowing that you'll ever find. It sets the table for two predictable outcomes. The first is that someone other than Thor could prove themselves worthy. The second is that Thor could also prove himself unworthy of Mjolnir. We've seen a number of stories on both of those fronts over the years.
It's too bad that you're not a fan of Beta Ray Bill. You're not alone; I've had similar discussions with several friends. In myths as you know, the gods all have different guises and different aspects. I always saw Bill as just another aspect of The God of Thunder. The only shocking thing to me was that Simonson went with an almost therianthrophic representation of Thor, like how worshippers of Egyptian deities would often depict their gods. Only instead of a bear or a hawk -- both of which were not uncommon pets for Vikings going waaaay back -- Simonson went with a horse. I'll admit that when I first saw him I wasn't the biggest fan of Bill's appearance, but in terms of a creator doing the unexpected, I was definitely blown away. That Bill was a noble warrior who returned Thor's hammer and ultimately gained one of his own was a nice touch. Love him or hate him, you have to admit that Stormbreaker is a pretty awesome-looking hammer.