I like them too as long as they aren't too bright and shrill. Part of it has to do with mic location - I just had it sitting on a table. If nothing else, they let you know it's not midi.
Noises like that are great if you have some stereo reverb because they fly around all the place and really add dimension to the recording. The problem is that it sounds less intimate. Also, outdoor sounds do not reverberate unless there's something for the sound to bounce off of, so reverb isn't always appropriate. To get sound sources to sound like they're further away without adding reverb, you roll off bass and treble frequencies, but that doesn't add a sense of left-right dimension to the recording in and of itself.
I always get a kick out of it when I'm watching some sort of TV show and the actors are talking with eachother in a cathedral or auditorium so there's a lot of echo. And then once they get into the parking lot, the echo doesn't disappear. You would think stuff like that would be easy to catch.
