Two things. First, when I read the topic, I misread it as "Exploding Thaumaturgy" which gave the topic an entirely different spin until I realized my mistake.
Secondly, how much of a real issue are Thaumaturgy themes really going to be? I can certainly understand how the hanky full of sunshine can be an issue for some, since it requires capturing a happy moment. That itself should be fairly easily compelled to control who can do it and when. Yes that means you emo sorcerer.
From what I've seen in play, one of the real limitations players are going to run into with Thamaturgy is their own imaginations. Case in point, a one shot game I ran at a convention involved a war party of Wardens descending on a city to hunt down a source of black magic. All the players except one were familiar with the Dresden Files novels, and all of them were also familiar with the DFRPG. They managed to find a portion of the diary of the person they were looking for, but completely forgot about using Divination to locate the other half of the book. Instead they were trying to break into a school office to go through the records... Ignoring the fact that all such things are computerized now...
Given how basic Divination is, and how often Harry uses it in the novels... For a party to completely forget that is an option for them suggests that players will have 'favorite' rituals which they'll use regularly, otherwise they'll likely not get too creative.
-Cheers