Everything goes back to the most important article ever written on public opinion, "The Nature of Belief Systems in Mass Publics," by Philip Converse. Very few people have coherent, well thought out "ideologies" that govern their opinions across a wide range of issues. At most, people have opinions on a small number of issues that affect the groups with which they identify. Thus, Converse argued that we could break the public up into "issue publics," that think about discrete issues relevant to them.
To whom is campaign finance directly relevant?
Campaign finance is a procedural issue. I am fascinated by electoral rules, but I am very, very weird. So are you, since you are reading this pretentious, little blog. Not only are you reading a pretentious, little blog, but you are reading a post about an obscure issue on said blog. Procedural issues, by definition, cannot have direct effects. At most, they have indirect effects on the process by which other policies are set. To those with only modest levels of political engagement, which is most of the electorate, that won't be a motivating issue.
Abortion is about either life and death, or control of one's body. Taxes are about either control of one's property, or funding of necessary services. We can keep going, but these types of issues will always be more motivating than anything procedural that only indirectly affects anything else, at best.
And then there's the fact that campaign contributions don't do anywhere near as much to influence policymaking as whiny goo-goos* assert, and I'll be dealing with that more too. For now, I'll reiterate my advice to read John Wright's Interest Groups & Congress. Serious scholarship has never shown money to be as influential as the conspiratorial ramblings of journalists and certain whiny lefties. Those latter just need a villain to explain their losses, just as the right needs the phantom of voter fraud to explain their losses.
Regardless, most voters just don't have enough room in their limited political attention to care about procedural stuff. So, they won't give their attention to stuff like the Clinton Foundation, campaign finance reform, etc.
* Derogatory term for "good government" advocates used by assholes like me.