I saw this talk in person at Nordic Ruby, and it was one of the best talks I've seen (and I've seen a bunch). Strangely enough, I don't really think back and think much about "optimism" when I think of the talk, though, even though the talk is about optimists.
My takeaway was the type of tooling and thought processes that are advantageous when approaching problems and conflict. In many talks — mine included — people will say something along the lines of "be nice to your teammates and leave good feedback", for example, but that's really vague. Reg's talk helped me understand what that type of feedback might be, how it can be explicitly phrased, and how I can give concrete feedback without being antagonistic. I think it makes for a more effective argument, especially when building product, but also it just makes for friendlier humans.
Yeah, this does lead to "optimistic people", hence the title, but I just thought it was weird to see discussion here about the merits of positive people versus negative people. I think the talk's a much bigger dialogue about interacting with humans and, possibly more importantly, yourself.
Anyway, I really liked the talk, and as much as this Markdown is great at getting the point across, this is one of the talks I'd suggest actually watching. \m/