I think any discussion of human rights is positive. Depending on who your counterparts are, it can have a very strong impact.
What has a strong impact is if your counterparts know what you're talking about; that they know you know what you're talking about, that you're not just talking about what you have read in The New York Times or from reports from Iran, but you know exactly what the problems are with the laws. So when they say the Iranian president is elected democratically, you can then tell them that is not the case, and no matter what your relationship is with the Iranian leadership, they know you know the leadership is not elected democratically.
These things are important. That's why I say you have to insist on your values and do not be lax on definitions and principles, because that is when they won't feel motivated for change. If they think you believe they are democratically elected, they have no reason to change the political party laws.