I think because Loki is curious and never fit into Asgardian society it kept his mind open to new cultures and understanding. Where Thor is an Asgardian hero and fits in his home world. Also Loki is like 10 times more intelligent than Thor.
Loki is so brilliant, it's mind blowing. He is so far ahead of everyone else. He wins the race before you even find the starting line, he's uncatchable. And when Loki knows what he wants, he will get it. The god of mischief and lies, indeed.