"Not all “cities” are important, some “towns” are very important. "
Would your judgement of importance be the same as mine? Seems to me that is unwise to try to classify according to subjective criteria when there is the reasonably objective criterion of population available. The mapping should show that each settlement is a population centre of a certain size. The current classification may not agree with the government’s but it fits in with general use.
The government designation could however be given to the municipal boundary, or a government classification tag.