It's not unlike a tragedy of the commons, clicking through Wikipedia maybe "Collective action problem" is even more apt? Individual app makers do things which they like and want without considering the wider implications of cross-app usability in the operating system.

In isolation many apps may be acceptable, but that falls down in the wider context.

The problem would be less of a problem if everyone did the same thing (bad or good UI) in a similar manner, because then there is predictability which is a powerful concept in user interaction.

Trinity Desktop Environment is a somewhat maintained fork of KDE3 with the same functional and understandable GUI.

The good examples are the software they replaced.