The thing that BB did wrong about android compatibility is that they went for the numbers. Going for large app numbers and making sideloading not-so-easy has the sideffect of attracting low quality apps from developers that don't want to make the effort to create a native app. On the other hand it doesn't solve the "killer app" problem (as manifested with the N9/whatsapp craze) as a serious company wouldn't want to provide inferior quality, ported app, so they probably won't bother at all. (Even skype, which they clearly took the pains to integrate the apk very well with the blackberry hub, is buggy and feels out-of-place).

It doesn't appeal to the masses who won't switch because of one killer app they use every day (be it instagram, skype, viber, whatsapp, angrybirds or whatever) as sideloading is a bit tedious and there's no legit way to transfer paid apps to your BB unless you already have an android device.

In my book android compatibility must be there for people to sideload things easily (and even be able to run the actual play store) so that they fill the gaps of native apps missing, not as a way to boost app numbers.