I personally avoid talking to customer's service as much as I can. I'm more likely to give up on a product or switch to alternatives than say anything. There are a very few exceptions to this. I suspect many other people are like me.
I can understand what you say about unhappy users, they are the hardest to establish a conversation with, in fact, I had yet no luck with them.
I also try to contact my most engaged and paying users, very little luck there.
So, either everyone is laying (very unlikely), or I'm doing something wrong.
I'm an engineer, so I can definitely think about products I use which I'd enjoy talking to the developers and designers. Sometimes they can be the owners too. But if they are more about getting a business running and started, I don't care about that stuff. So, I wouldn't personally want to talk. I suspect people who are interested in running a business would like that. So, maybe your users are not mainly from that segment of the population.
I'd be willing to accept $100/hr from someone I'm paying $100/month to, but I wouldn't care for $25/hr from someone I'm paying $25/year to.