Could somebody explain why it was tied to SMS in the first place? And given that, why it's trying to undo its connection to SMS? Separately, what's the differe

Could somebody explain why it was tied to SMS in the first place? And given that, why it's trying to undo its connection to SMS? Separately, what's the difference between this and OTR? Is it just trying to just be a better OTR (and I support this endeavor, competing OTR connections over one chat channel creates a hassle). And as such, why is it only on Android, you could just as well write a Pidgin plugin right?