I cant understand why someone would be dissapointed if you encountered a friendly dragon. Im sure if there was one, it would fit the story.
Because for me personally, it would be boring in comparison to what I anticipate instead. I see the dragons as comparable to a force of nature and their mission as non-negotiable. The inevitable cosmic result of a massive kalpa-spanning metaphysical equation. The thought and will of Time made manifest.
To my tastes, having a friendly or neutral dragon who doesn't care, something that is an outlier, something that makes dragons just dragons, just doesn't compare.