The reason that comic book movies are never as good as the originals is that the studios feel they have to mainstream the magic out of them. Too cheesy, too unbelievable, too colorful. It's a superhero movie, for crying out loud-- do it right. Holding back on imagination and creativity is not the way to adapt a concept based on imagination and creativity.
You're contradicting yourself. How is it imaginative or creative to slavishly copy what Jack Kirby did half a century ago? Come on, Galactus is a vast, incomprehensible cosmic force that's existed since the dawn of the universe. Making him a giant humanoid in a silly hat is one of the
least imaginative ways possible to interpret such a thing.
I don't care about "mainstream." I am not a person who would
ever favor something just because it was mainstream. I love the unusual, the exotic, the challenging, the iconoclastic. I love ideas that transcend the everyday. And that's exactly why the idea of a cosmic force like Galactus having a humanoid shape is so completely boring to me. The human form
is mainstream. It's ordinary. It's familiar. It's a tremendous failure of imagination to envision a transcendent cosmic entity as just a bigger version of a human. There's got to be something more exotic, more creative than that, and I'm sure there's something more creative than the swarm of particles we got in the previous movie. (Although that was inspired by the Gah Lak Tus of the Ultimate Universe, which I think is a very clever reinterpretation.) Something that really says "cosmic force" or "entity so vast it consumes planets."
As I said, something like V'Ger could work for me. Or maybe something like Solaris from the Soderbergh movie. Or a mix of elements of both. Or what if Galactus were something like a sentient black hole? A pucker in spacetime,
distorting the light around it, but maybe girdled by bright, complex, colorful energy fields that contain Galactus's consciousness (make them purplish as a nod to the original). Perhaps orbited by some vast Kirbyesque devices which could be interpreted as instruments his heralds have constructed to facilitate his feeding, and which could descend and unfold (or deploy pincers evoking G's helmet) to encircle the Earth and prepare it for consumption. How's that for imaginative?