- funding (ICO) - an economic incentive for attracting early users (give tokens for using your app in the promise that they will be worth more in the future)
b) if a user earns tokens that value over time, that's a huge win: imagine if all the time you spend on apps today, generating valuable data to a few companies, would generate in turn some of these tokens back to you?
Besides, what do you mean by "closed" exactly? The data being on the public blockchain should actually encourage integration by default. For example, several new dapps are being built on top of IPFS for data, using uPort for identity, Aragon for governance, etc.