Theme slaughter is tiresome but fun. Although many themes are useless, a lot of them instigate nice ideas. Out of 3360, I kept only 69 themes (~2%). The slaughter question is "Would this be a good Theme?" but near the end, I realized that I was answering a different question: "Do you like this theme?". Looking back, I should have been more open and kept much more themes.

My personal view about themes
I believe that restrictions should only be a side effect of the theme and the main goal should be inspiration. That's why themes should be broad as long as you can discern games that follow it from those who don't. For example, GGJ 2015 theme "What do we do now?" is too broad because anything can fit in. I see themes as a tool to break creative blocks (like randomly browsing a dictionary) by motivating the mind to explore new possibilities outside its current box.
In the 3 GGJs and 3 LD jams I participated in, I feel that GGJ submissions had more diversity in theme interpretations compared to LD. My hypothesis is that GGJ themes translate to personal experiences while most LD themes translate to game mechanics. For example, GGJ16 "Rituals" has no translation to game mechanics and its interpretation differs with culture, age, gender, activities and so on. GGJ 17 "Waves" is broad too and can be seen as sea waves, sound, light, signals, enemy waves, heat waves, trend waves, mood waves and so on depending on your background.
On the other hand, LD39 "Running out of Power" easily translates to "limited and consumable resources" (energy, fuel, moves, time, etc). LD40 "The more you have, the worse it is" is very similar to "The game gets harder as you make more progress" so many games just increased the difficulty when you collect coins, items, etc. Some games still had their unique interpretations. LD41 "Combine 2 Incompatible Genres" had more diversity since it has no obvious translation into certain game mechanics.
The main thing I like about LD is that even if many submissions in LD 39 & 40 interpreted the theme as similar mechanics, they still experimented with many unusual combinations with other mechanics and genres.
What do you think?