Because Google Play will be rejecting APKs in a few months.
I believe it’s also really important for this to be added so if people already have apps up on google play, they’re actually capable of updating them. The updated games need to be packaged with gdevelop’s signing key or google play wont accept them. I don’t -think- decompiling the app and manually packaging it with android studio, if that’s even possible (I’m having a nightmare of a time trying to figure out how it works), will allow people to just carry over Gdevelop’s key, though I may be wrong.