I completely agree that most of these celebrity "scandals" fall somewhere between silly and ridiculous, but I wonder if there's a slightly different reason behind the seemingly old fashioned standards.
Look at what now constitutes a celebrity. It would be bad form (and probably against the rules here) to name names, but I'm thinking of the reality show star/internet personality/celebrity-for-no-fathomable-reason types. Think about what it takes for those people to actually be caught in a legitimate scandal, one that has ramifications for their public standing. Sleeping around or getting into a fight is briefly intriguing, but it takes a lot worse to tank someone's repuration. Is that really the kind of thing that could be implemented in a Sims game? Would we want it? And how would that even work with the teen rating? I mean, I'd love more mature themes in TS3, but not particularly along those lines.
Or, for that matter, consider how some of these people got famous in the first place, for things like... um... a particular kind of home video. As much as I want my sims to have their fun, I don't think they need to make recordings. And I definitely wouldn't want said recordings to be available on the internet for everyone in the entire sim-world to view, no matter how famous my own sims would end up being.