There's a setting to show pattern directly on every ROM I've seen so far. If your ROM doesn't support it - blame your manufacturer. You can disable it easily. Look for privacy options. My three button headset works as it should. Tried in LineageOS and MIUI8. You're right about Samsung. Unlike with iOS you can have the full source code of Android and you can modify it in any way you like. Lot's of people do. So mantra changes in this case like "if you don't like it, do it yourself" IMO, Android got much better than it was before.