There is a moment in Chapter 54 of the Love Hina manga that perfectly exemplifies the two main themes that ensured the series' success: Emotional resonance punctuated with giant robots.
You see, a romantic is not someone obsessed with affection and happiness. A romantic is someone who in the absence of affection and happiness retains a (usually unjustifiable) confidence in hope.
Love Hina is richly steeped in romance. However, from a creative perspective, romance alone is not enough. Giant robots—the absurd, the unexpected—are also occasionally needed in the calculus. It's the yin-yang thing at work, y'know.
The presence of the former without the latter can cause an otherwise sweet story to become saccharine. Likewise, the presence of the latter without the former will often prevent an audience from developing an emotional commitment strong enough to care about the characters or the direction of the narrative.
This is hardly an original idea. Fans of Buffy the Vampire Slayer will recognize this theorem from a similar statement made by Joss Whedon on the Season Two DVDs. (I am substituting "giant robots" for Whedon's "rocket launchers," but the reasoning is unchanged.)
I am mentioning all of this for two reasons. First, with the new fall television season upon us, I think you'll notice that the success or failure of any given show will depend heavily on how it balances these two thematic elements. Although it is a fairly trivial matter to predict a new show's future by measuring the amount of pure, unadulterated suck it delivers through one's television set, nevertheless, it may be interesting to evaluate the shortcomings objectively. Second, I just wanted to say in a roundabout, excessively verbose, indirect way that the Love Hina manga is like the best thing ever—even better than the anime. Rest assured that despite being 14 books long, it doesn't have nearly as much filler as I've posted here today.
Be sure to tune in next time when I post my 29,000-word thesis on why Asuka wears her plug suit's hair clips all the time. (Short answer: Asuka interprets her own personal worth solely through her identity as an Eva pilot. Bonus answer: Similarly, Shinji uses his SDAT player to physically manifest what Ritsuko calls his "hedgehog's dilemma.") And there will be more fan service, too!