Mal was always a trifle sociopathic. The scene in "The Train Job" where he just offs the villain guy after his token intimidating speech comes to mind (or shooting a guy in mid-sentence in "Serenity"). It's part of his cool, badass, all-American attitude: If you can solve a problem quickly and effectively with a gun, why not?
I was willing to roll with that, moreso than I was Firefly's
tendency to romanticise him as an honourable thief (I assume Whedon figured audiences wouldn't like a show about a mere small-time smuggler, or maybe he just didn't like the idea... given our desire to see heroes, he may have a point there.)
Joss wasn't the only worldbuilder involved though; I'd be curious to see how much Tim's input went in. Also, Firefly's universe is, overall, still better constructed than most television sci-fi universes.
I found Firefly's
universe the weakest aspect of the series. That's not a matter of plausibility when compared to other space opera universes - just how well thought out and/or interesting I considered it compared to other space opera universes. The show's strength are the characters and stories, but it's really best not to think about the universe in episodes like, say, "Hearts of Gold", which is so unapologetically a Western cliche it crossed my mind why they even bothered using the spaceship in the climax.
At its heart, Firefly
is of a mind with every single 'write a Western and tack on IN SPACE' cliche from the 1930s. It's not even spacing up Western cliches, it's just presenting them without comment (compare the Mos Eisley Cantina, Star Wars
's 'spacey' version of the Western tavern of disreputable sort, to the numerous rote depictions of actual regular Western taverns of the disreputable sort on Firefly
It does it a lot better than most of the more literal Western SF, and the addition of Mandarin and some Chinese references keeps the universe from feeling Anglocentric, and the whole 'lived-in' environment and designs, costuming, etc. are all above par... I guess what I'm saying is the Fireflyverse is a helluva lot better realised then it was thought out. A decent budget, sensible design and good writing raised what otherwise could have been a pretty awkward premise to success.
And the big problem for me with the Reavers in Serenity
is when we finally see them they're about as frightening and credible as Andromeda's
Magog. Heck, Magog are apt in general: Both series go on and on telling us how awesomely evil and rapaciously disgusting these creatures are, but in the flesh they're just guys with ugly makeup/goofy suits jumping about.
may have been better served by never or rarely showing the Reavers in its entire run, the less we knew of them the more effective they were.