Well the comedy didn't hurt the movie for me. Honestly, this goes all the way back to RD's humor in the first Iron Man. Comedy, particularly of a screwball nature, is kind of woven into the MCU's DNA at this point, for better or worse. And for example, as I found Malekith such a poor villain, stuff like Thor having to take the subway during the final fight or Darcy making out with Ian while a giant Ice Monster terrorizes downtown London made it far more enjoyable, because Malekith was such a non-entity for me that I didn't care that much about Thor hitting him with the hammer. The madcap zaniness elevated what would have been an otherwise rote climax (IMO).
As for more backstory for Malekith improving him? Possibly. But I think the approach was all wrong. Not only did he have motivation, but he was boring. The best bits of the movie, which will surprise no one, are when Loki is on screen. I don't even think Loki is a great "villain" per se (he's not threatening in the least), but he is a great character and charismatic to watch. Christopher Eccleston is a decent actor (though not my favorite Doctor), but he was given nothing to work with. Malekith is just too monotone and one-note.
What could have been given more breathing room is Thor's relationship with Odin about becoming king, as well as Thor's relationship with Jane before **** hits the fan, especially with his mama involved. All of that could have been given more depth. I think Malekith was a lost cause though.