I feel like for most people that jail break, the things that they choose to use jailbreaking for are small modifications to the way their phone works. If there was a market where you could buy small modifications to the phone, most people who jailbreak now wouldn't. Apple would probably put some limitations on what the plugins could do, but I still think it would improve iOS devices significantly and mitigate many of the advantages that Android has. I know there will also always be apps that people will want to use that Apple wouldn't allow, but this conversation isn't really about that. A better description is probably modification store.