Most professions on the list don't have a shortage, and professions stay on the list for far longer than necessary. We don't need any more IT workers, for instance; my workplace routinely receives hundreds of applications even for temporary roles.
We get to set the terms of migration, because it's our country. I don't think we should be allowing students to bring dependents across, for instance, because they're students. We're already saturated with them, and could stand to be a bit more exclusive.