If you haven't already, read this article. It's a sobering, thoughtful critique of designdom's optimism. I was taught in school that designers could design anything. Once we learned "design thinking" we could approach and solve any problem. Research, user ethnography, brainstorming, mapping, prototyping, testing, validation, second prototypes, etc...it's a pretty powerful paradigm, to be sure. It sounds a lot like the scientific method in many ways...and makes us think we can solve the world's problems.
"In particular, design metaphors obscure the ideological—and political—decisions involved in tackling societal issues. Depending on your perspective, “drunk driving” can be a symptom of some broader systemic failure (from un-walkable suburbs to deficient public education), a lapse of individual responsibility, or a right to be defended. The solution to the problem is inseparable from its conception. Conceiving of global ills as design challenges may sometimes be in order, but only when a consensus exists on goals, budgets and relevant values. Such is rarely the case."
While I share the optimism of my time...that design can change the world, I think taking a moment to realize that great designs often fail to catch on is worthwhile. We can think great thoughts, design wonderful social systems and processes, but we can't make the horse drink. Maybe it wasn't really good design, then, if it didn't catch on...or the market got in the way, the time wasn't right,etc. In the end we can't design everything. We can't design the market or the user or a thousand other factors that effect our efforts. But that shouldn't stop us from trying.