I might be wrong, but I thought
Odin was the chief god, not
Thor. And besides, in Greece, there were plenty of Apollo-names and Hera-names.
My guess is that it's because among some ancient Norse people,
Thor was the most popular god, being the honsest, hardworking blacksmith he was.
Or maybe it was simpler than that; maybe it was just that "
Thor" was only one syllable and was easier to combind phrases to. Just my two cents. :-)