Users are well within their rights to do just about anything, including insult the developers mother. The issue isn't what their rights are, the issue is with etiquette.
Politely requesting features from developers you are not paying is not a breach of etiquette. Saying "No." in response to those requests is not a breach of etiquette. Making demands of developers that you are not paying is a breach of etiquette.
Politely requesting features from developers you are not paying is not a breach of etiquette. Saying "No." in response to those requests is not a breach of etiquette. Making demands of developers that you are not paying is a breach of etiquette.