there has been plenty of ink spilled on the influence of the Religious Right in politics, but its influence as a major independent variable has waned considerably, hence less fodder for the journals.
Agreed, and I think that's due to it being a fairly unreliable (weak, easily influenced by exogenous factors) independent variable. For instance, tracking data in polling such as the American National Election Study shows a less than sexy (highly technical political science jargon at use) correlation between religions and voting patterns. Also, strong correlations, such as U.S. Jews to Liberalism, or weak but positive correlations, such as U.S. Catholics to Liberalism are not necessarily influenced by the religion itself, but more likely by socio-economic factors, historical/cultural trends.
You're right though, when there appears to be a story, e.g. "Evangelicals won't vote for..." academia, much like the media, tends to get more interested. When voting trends can be largely and better explained by other factors, e.g. economic indicators, length of party incumbency, etc. interest seems to fade a bit.
What's always twisted my brain a bit was that Religious Studies typically attempts to study religions without the consideration of God or
various deities. Would it be impossible to factor in? Perhaps difficult and extremely limited, but I don't believe so. Of course if it was suggested that God be factored in, most would probably abandon their humanities credentials and claim that this would violate the principles of social science.