i assume currently quite a few people are using the Push Test Server: http://push-test.mattermost.com.
As far as i understand the iOS and Android App that are published on the App Stores are compiled with the respective Developer Keys. So if you want to use your own push Server you have to go all through the Process yourself.
Some People could probably have a hard time to A) pay for their own Apple Dev Account and B) distribute their self compiled apps to their Members. C) Could be some other reasons that i havent thought of now.
Do you have plans to transitiion the http://push-test.mattermost.com Server to some kind of Public Push Server? Or perhaps against a small fee?