I think that if we had a need to apply perfect pitch, more of us could develop and use it. I can often predict the key of a tune that I hear regularly (e.g. certain radio and TV theme tunes) just before it starts. If I really wanted or needed to, I could work from one of those notes/keys and identify or sing any other note. It would take a bit of practice but I think I could do it,and soon I'd be able to identify the key of any music I heard, or pull any given note out of the air.
But this would work against several useful things I can do when I'm singing or playing. For a simple tune, I can look at a written score, see how the melody goes, and sing or play it in a different key. I don't actually "transpose", really, I just use the written dots to show me the shape of the melody, the intervals and the rhythm. If it's not a comfortable range for my voice, I'll shift it up or down a tone or so and try again.
So if I had cultivated perfect pitch, I'd have the mental discomfort of seeing one written note, knowing for sure how it should sound, and having to sing something different, or of remembering a tune as being fixed in particular key and finding it difficult to move it into a new key. Ideally, you need to be able to switch off your perfect-pitch sensors at will, but I don't know if that's easily done?

Marje