Conservative innovation as a path to better user experience. Avoid Feature Debt.

Designing sustainable user interface is a very hard task that could take a large number of retries. The wider an established user group is, the more conservative user interface design changes should be. If a complete user interface overhaul is required it may work out much better to present an entirely new product to users. Doing that sets an expectation of a new experience, this gives an adequate cognitive comfort to users.