A lot of dapps seem like nothing new to me and the added benefit of creating a dapp seems very minimal besides decentralization.
Making an Ethereum-backed web application gives you several things for free:
- Payment processing: No need to integrate with Stripe or PayPal to accept funds from users. All users can send/receive Ether as a common payment means.
- User Credentials: Users don't need to sign up; they already have an account, which is a public/private key to bind with their user session and metadata.
- Database: Storing a lot of data in the blockchain is expensive, so likely the blockchain isn't going to be the only database for the application, but mission-critical pieces of data can be stored forever on the blockchain.
- Logging: Etherum contracts can create their own logs, which a DApp can query to know what's happened in the past, rather than needing to create separate logs.
If you're planning on using any of these in your application, either initially or long-term, building as Ethereum-backed (a DApp) gives it a nice head-start.
Decentralized app (DApp) is an app either mobile or web which interacts with a smart contract. The main benefit is to have a decentralized protocol as a backend to operate with stored value:
- without trusted intermediaries
- on predefined terms
- in deterministic manner
Check out State of dapps for inspirations https://dapps.ethercasts.com
The most important type of dApp is a crowd sale web app for ICO using ECR20 tokens