I agree for sure. I miss interactions like kiss up arm, jump into arms, and the animations of couples cuddling in bed. Turn ons/turn offs. Give Sims personal preferences in what they find attractive, so they don't flirt randomly. Also, this one doesn't have to be specific to romantic relationships, but I feel like there should be a way for Sims to develop kind of a love/hate relationship, or have mixed feelings about each other. Like, relationships where Sims tease and bicker more often than not, but aren't genuine enemies. Or where one Sim idolizes another, or is shy about socializing with people they like. I don't know how this would be represented on the relationship meters, maybe another color besides green/pink/red, but I dunno, I think it'd be cool. :P
(Also, maybe let vampires bite their romantic interests on the neck without having to compel them into it. With a kinder and gentler animation, of course...)