A lot of Apple products are designed to best work with other Apple products, that's part of their selling point. Would it not be easier to just buy non Apple headphones if you are not in the Apple eco system?
Yet if someone likes the sound quality, fit, or ANC of AirPods (which are genuinely good), why should they lose out on functionality just because they're not using an iPhone?
I'm all for everything being compatible with everything, but why should apple invest resources in testing/debugging android compatibility for something that they make?