[apache]

I understand what you are saying, but all that ecosystem stuff really does fall under planet conditions. But I do agree with your assessment that a planet with really bad conditions should force the colonists to live in a dome, regardless of atmosphere type. Perhaps some planet with 'Harsh' or worse conditions would force the building of a dome on the planet until conditions improve above that level.
Of course, the problem is that no planet naturally occurs as a 'Harsh' planet. They are all 'Unpleasant' or better. This I would like to see changed. Planets should naturally occur as 'Deadly' or 'Harsh'.