Most of the time they're used for a quick visual confirmation that "your operation went right"
The information that the user did something "right" should be responsive next to where the user initiated the action- not in a random corner.
I'm sure any reasonable person would agree; the more poignant question is whether you are sparing your future children or destroying some future children in favor of others. The former is something I hope any reasonable person would agree with; the latter is tantamount to eugenics.