If past experiences are an indicator, the security model itself doesn't matter - apps will simply request the widest permissions they can get away with, and use

If past experiences are an indicator, the security model itself doesn't matter - apps will simply request the widest permissions they can get away with, and users will be hammered with them until they give up and comply; eventually your calculator has access to your contacts, data, usage history and network. The only thing stopping this is the review process. Most app publishers do not have their incentives aligned in the users' direction.