The thing is, when it comes to campaign finance, he's not saying anything Hillary hasn't been. They'd both appoint the right judges. There's literally no space between them on this.
The reason he's derided as a single issue candidate is his inability to talk about anything else without going back to Wall Street and the Millionaires and Billionaires. He's shown no intellectual curiosity outside of that sphere. Just look at his foreign policy answers, he hasnt gotten any better over the course of this. That's the issue people have and they have that issue because the presidency is a multifaceted job and you dont always get to pick what you deal with on a specific day.