The standard DNS protocol is completely unencrypted and unauthenticated. That means that it can be both intercepted and redirected to a completely different DNS server than the one you think
you are using, so not only can your DNS traffic be captured and perused in-flight, all of your DNS requests to 184.108.40.206 (Google DNS) could be silently redirected to an NSA or CIA DNS server cluster and you would have no way of knowing.
DNSCrypt solves both of these issues by a)
encrypting the DNS request before it is transmitted from your computer and b)
cryptographically verifying that the DNS server you are
talking to is the one you intended
to talk to.
Of course that doesn't solve the issue of the DNS server operator logging every request you make to the DNS server (it's their server, so of course they can log your requests), but that's an entirely separate issue.
There's no reason to not
use it, tbh.