I see where you’re coming from, but I can’t help but wonder if a more cheerful approach isn’t also possible and perhaps even more conducive to impact. Julia Wise’s thoughts in http://www.givinggladly.com/2013/06/cheerfully.html and also especially Nate Soares’ https://mindingourway.com/detach-the-grim-o-meter/ would perhaps go in that direction. Basically: Being grim kind of sucks long-term. And maybe being more positive will lead to more impact.
But without further empirical data this is just speculation on my part :P
(Just as a couple of thoughts that are better than my n=1: In community building the recommendation is opportunity, rather than obligation, framing, so it probably works better? I recall there also being some studies on advertisements with negative/positive/humorous tone, and the latter two had better effects. Probably low external validity though. Also, though, comedians like John Oliver probably have a much higher reach compared to the usual by just being, well, entertaining and fun.)
This one now requires you to sign up, which is a bit unwieldy. I went for the 80k article instead, but let me know if there’s an easier way!