We should try to keep some order when it comes to tags. Do we already have an order? If not which rules do you suggest? Can I just create a tag if I feel that an important tag is missing?
If you have the reputation to reach the correct level of privilege (which you do), then you can create tags.
However, with a mature site like this one, you're encouraged to think carefully about creating new tags (almost any tag of lasting value will either already exist or there will be a similar one which will compete with a new tag). If there's any doubt about how a possible new tag fits into the current tags, for example, you can always discuss it on meta.