o.O That's without a doubt one of the greatest OSTs of all time. I love it and it makes me feel all epic when I'm playing.
I don't really feel like art style says anything about what type of music is appropriate with it. The tone and mood of a game are better indicators of what is or isn't thematically apropo. I think they matched the game well in that regard.
Not catchy? I find myself humming/singing/whistling/playing Gusty Galaxy and Good Egg Galaxy all the time. For that matter, what's not catchy about John Williams. You've never gotten the Indiana Jones theme in your head? Jurassic Park? Star Wars? Etc.?