Odin hungers. And thirsts. He wants to know as much as He can about absolutely everything He can. And His thirst is never satiated it seems. This is what caused Him to sacrifice one of His eyes for one drink of the enchanted waters from Mimir’s well. This did give Him immense knowledge, but it also made Him crave even more knowledge. When you get down to it, that’s what Odin is–that intense craving for yet more and more knowledge and power. This isn’t a bad thing, it’s just something to recognize. He is the wisest of all Gods, of all beings everywhere, and this is a title He bears with pride and joy. Why wouldn’t He after sacrificing an eye to gain some of that knowledge?
I myself have a thirst for knowledge, much like the Allfather does. But I can’t imagine sacrificing one of my eyes for such a thing. You would think it would be better to have both eyes–that it would be easier to observe, see and learn knew things with two. But I have a theory. I don’t think Odin is blind in one eye. He may only have one physical eyeball, but I don’t think He only sees out of one.
My theory is this.
That with the one physical eye that He still has, He sees the mundane world. Our world. The world of Midgard. When He sits on Valaskjalf, this is how He sees what all is going on here. But out of the other “eye”, He sees everything not of our world. It allows Him to see into the spirit realm and everything that goes on there. This is how He is able to see ALL when He sits on Valaskjalf.