Are developer roadmaps beneficial or harmful?

[joelr]

There are a lot of competing perspectives about roadmaps.

Consumers demand them, because it gives us guidance on what we can - and cannot! - expect, so we don't have to invest in an expensive custom mod if we know something is coming.

Developers may not want to share their roadmaps, but it may force them into a situation where they need to explain a cancellation of a feature.