Now that I've grabbed you with a clickbait title, let me amend: interface changes come to the table with an inherent very large negative value attached. Unless the value offered by the change is extremely high, the cost of breaking people's familiarity and use cases will vastly outweigh the benefits.
I'm specifically talking about user interfaces, here, not APIs, but I do think the same principle applies; however, APIs tend to be well-defined with simple semantics, so dealing with changes is easier and the initial cost is lower. However, with a big enough overhaul for little enough benefit or with poor enough documentation, APIs can easily fall foul of this as well. Consider Python 3, for instance, which after seven years still has remarkably poor adoption.