...I wasn't sure how thoroughly I COULD analyze the film or any of the rest of the series, because really, it's mostly "Kate Beckinsale is hot, so let's watch her be hot wearing hot clothes which accentuate that she's hot, shall we?"
Sounds to me like you understand
Underworld perfectly.
Well, I mean, I really DO think there's some substance to the movies as their own encapsulated universe with its own rules, as per their depiction of virus/infection-based Vampires and Werewolves, versus the traditional supernatural sort. There's plenty of points to consider about how their anatomies work, how their social structures exist, their explained historical development, and how they now fit into the modern world. For instance, that the Vampire Coven Selene belongs to owning major medical corporations that "skim off the top" of all blood transfusion donations, thus how they satiate their thirsts while remaining incognito. Nifty little detail, which I found amusing. Of course there's more to the films, and overall I kinda liked the first two.
But it was when I tried delving deeper into their flaws, their loopholes, plotholes, holes of any kind (giggity giggidy?) and inconsistencies that I couldn't shake the feeling that there was more looming over the films than convenience and plot contrivances. Oh, sure, this one character has lived for roughly 2 millenia, but now that he's shared a dramatic confrontation scene with the main character, let's just throw out 2000 years of convention and countless lifetimes of having resolves to keep on living because he's conveniently decided that now's the perfect time to end his own life. Makes PERFECT sense! Sure, that was a glaringly poorly-written plot point, but there were greater problems plaguing the series than moments like that.
I just came to the conclusion that it was the series' obsession with Kate Beckinsale as a carnal focus that seemed to explain it all. It was just glorification of her amazing assets, in tight glistening leather-covered latex with obligatory corset for no reason. I could dwell on how their combat in the films was gimmicky at times, and inconsistent at other times, but then come short as this is indicative of all movies everywhere. I could fixate on the sexualization of this pseudo-goth lifetstyle. I could nitpick on how EVERYONE feels compelled to wear black for some unexplained reason. But it would be missing the point that the films had their failsafe in place for any and all of these potential dilemmas, all along. Kate Beckinsale is hot, let's dress her up to be even more visually hot, let's give her a unique variation of supposedly-standard combat techniques that routinely pose and land her in hot manners, and for God's sake SHE'S HOT!!!