The release and tweak model works well for web apps -- today. Because there is no real review model for web apps.
Mobile apps are a lot more like movies. Opening weekend means a LOT. If you are weak out the gate, you'll have bad reviews. When you update, no one will care, because not many people will buy the updated app because of all the one-star reviews.
The only time this doesn't apply is if you a huge built in userbase like Facebook, where even with bad reviews, people will still get the updated version of the app.
For Android, the market can be avoided by just offering the .apk file (e.g. you can self-host the .apk and only share the link with a select group, or if that's not secure enough, require a unique key to unlock the app once it's loaded).
Mobile apps are a lot more like movies. Opening weekend means a LOT. If you are weak out the gate, you'll have bad reviews. When you update, no one will care, because not many people will buy the updated app because of all the one-star reviews.
The only time this doesn't apply is if you a huge built in userbase like Facebook, where even with bad reviews, people will still get the updated version of the app.