Like others here I feel poor documentation is the most painful issue. Languages, IDEs, operating systems, and frameworks all have major problems with this. There is a very old joke that goes: "When they finally teach computers to understand English, they will realize that programmers can't speak English." There are reasons for this. To succeed, programmers must reduce complex ideas to mental symbols that can be manipulated without articulation. It is hard to achieve this ability and painful to go in the reverse direction.

There are times when programmers evade the responsibility to document their efforts and even times when so-called documentation is a patent fraud, a pretense at documentation. In general failure to adequately document your work is un-professional and degrades the profession. Just coding is not professional it is a subprofessional technical career.