My VPN provider (Torguard) provides one of these as well. I'm a little more willing to trust them not to do anything malicious with my DNS requests, if only because I'm paying them.
The bottom line is, if your information is valuable, then it will be in the advantage of those who possess it to exploit it whether you pay them or not. The only real non-moralistic consideration is whether you will stop paying if they start selling.
Either way, "I have a moral obligation to not sell your info, even if you don't pay me not to" sounds a lot better to me than "I don't sell your info because you think you're paying me not to." It's a horse apiece if you're dealing with strangers and you have to take them at their word.
Thinking about companies I've seen the inside of, when the company is doing ok, it's rare for people to just up and do something sleazy. But if they company could collapse, suddenly the moral calculus shifts. Even if they don't do something dubious, they often will consider revenue sources they would have ignored before. As they say, desperate times call for desperate measures.
So I'm much more likely to trust a company I'm paying a fair rate for what they're doing. That's not to say that those people don't turn bad sometimes, but it happens a lot less.