If anything, I feel I'd be adding weight to the aircraft unnecessarily. Every ounce counts.
DJI has a slew of about 700 engineers (Desing - Electrical - Mechanical to mention a few), dedicated to the development and testing of new designs. It would not surprise me if at one point in the early stages of the design of the Phantom metal quick release was considered an option. Perhaps during testing it was discovered that "metal" quick release locks adds more weight resulting in more battery consumption = less flight time.
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