You're right, a lot of those problems aren't sexy. Yet, they're all critical problems that must be solved.
That said, some of them are sexy. Voice-to-voice translation, for example, is already being worked on substantially.
Most of those problems, though, seem to me to be more political problems than technological ones. The cost of housing in cities, the failure to help refugees and displaced persons, tools for collective decision-making, and infrastructure in the developing world are not problems that can be solved by throwing technology at them. These are political problems. In technological senses, every single one of these items is known, understood, and holds few mysteries for execution. In every single one of these cases, there are real obstacles that generally cannot be removed by technology.
Maybe someone wants to launch a startup to convince cities to permit housing to be built? Of course, I'm pretty sure that would be a lobbying group or advocacy non-profit... things that already exist and work very differently.
People do very often just grab for the sexiest problem at hand. There are always other problems that could be solved. Yet, it's perhaps possible that the startup model isn't the right tool for every problem