ISP's can do awful things to traffic. I'm not sure why you should trust your ISP and if anything trusting makes you blinkered to some of their practices.
For me the point is: why would you trust a VPN provider any more than you trust an ISP? There might be specific reasons for specific providers, but in general you're putting the same amount of trust in either way.
Maybe you are not in the United States, but for those that are, the answer is pretty simple.
It is reasonable to trust a VPN provider more than an ISP because you have a choice of VPN provider, you can vet them and choose the one that you feel provides the best safeguards to your privacy and security. Most Americans have between zero and one choices for high speed internet. Even in major metropolitan areas it is common to live in a cable monopoly, with a phone company providing sub-par "competition". You cannot vet your choice and choose the one that provides the best experience because you have no options. Even those that do have a choice may still connect to coffee shop or hotel WiFi on occasion, losing choice again.
In short, VPN providers are a) competitive and b) portable.
You're not wrong that you're putting the same amount of trust in them, but these properties mean you would not be wrong to do so.
Some VPN providers have paid for external audits to verify their processes; they can also exist in countries with more favorable privacy laws. ISPs of course are local to you and your jurisdiction.
And that is a fair point. I don't see why you would simply use an alternative DNS resolver in that case and not get a VPN or an SSH tunnel or something?
