[Quiet Man Cometh]

War time does mean things to people. That's the main thing I can think of. Compare the time when Morgoth was running amok to the Hobbit era and things must have seemed more cheery to them. Being interested in celebrating or in creating works of art and poetry or whatnot doesn't mean someone can't kid ass when they want/need to. That's just a general statement though. I've only seen the elves in the LOTR series so there's not much I can say about the Silmarillion elves that isn't hearsay. They did come off as more serious in Children of Hurin from what I read but again we're dealing with a different age on Middle Earth when Morgoth was moving around.