I think one of the biggest fails is that most of them are an action to cast. For such minor and often non-combat abilities, it ruins any really neat effects to waste an action in combat to do them.
For example: Thaumaturgy has several useless-but-cool looking effects like causing candles to flicker, doors to slam shut, or thunderclaps to happen. That would be awesome in combat if you moved across the battlefield to your enemies while spooky stuff was happening. But it costs an action to start the effect, meaning you can do anything useful like attack or cast a real spell while looking cool. If it were a bonus action, it wouldn't feel like such a waste of action economy (assuming you had nothing else going on with your bonus action, look cool is a viable use). but as is it requiring far too much setup for such a minor effect.