I was gonna say the trees seem to lack of sense of delicacy, but frankly it amuses me more to assume that they're doing this on purpose to get back at people for turning them into trees in the first place.
"Yeah, photosynthesis turned out to be a sweet deal, but I miss being able to fly, y'know?"
"Would have been nice if they'd at least asked us first--ooh, here they come! Quick, get your roasts ready!"
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