User blog comment:Lia Schiffer/ANIME SPECIAL: 268: Hatred and Jealousy, Orihime's Dilemma/@comment-893506-20100502054628

Since I grew up being introduced to anime via dubs, I actually lean more towards the first name thing, but overall, I can watch both. Like you said, it's probably just a matter of personal tastes. Still, cultural-wise, being addressed by last names in English isn't common, so it wouldn't do well with dubs. It's not non-existent though, and there have been some instances where Uryu Ishida calls Ichigo "Kurosaki", and others have used last names from time to time.

I don't recall Rukia calling him "Captain Kaien" in the English dub ("Lieutenant Kaien" is probably as far as they got with rank), but that could be awkward too.