When I see opinionated I assume that the developer made a decision that they like, but they know some people won't like. They are saying up front that they are

When I see opinionated I assume that the developer made a decision that they like, but they know some people won't like. They are saying up front that they aren't trying to satisfy everyone. They're doing it this way, so don't open up issues asking them to support doing it another way.