Williams did write Hearth's Warming Eve, which is one of my favorite episodes. Then again, she wrote Mare Do Well...
I don't particularly like her writing style, but she's written mostly for shows that rely on a very different kind of humor and characterization, (i.e. Camp Lazlo and Spongebob) so it's understandable. At least it's better than her previous episodes.
Rarity was a bit over the top in this episode, I'll admit. Spike wanted to hang out with the older dragons rather than the ones closer to his age because he thought they were "cool", I guess.