I think your last point is heavily situation-dependent. What you really want to do is maximize the area of your Voronoi-diagram: the problem space for which you or resources you control are the best available solution. Sometimes the best way to do this is to eliminate a weakness, so that it's no longer a dealbreaker for people that wish to use you as a solution. But many times, the best way is to perfect your strengths, so that you're clearly better than the alternatives around you. People are willing to forgive and work around many weaknesses if you're very, very good at your strengths.