Going out on a limb a bit here but I guess it might have something to do with the claim culture in some societies as well. Some pilots get in trouble before they even get near the demonstrated number and the wording may have been chosen to avoid claims after such incidents. You could also argue that it makes the aircraft more flexible to operate. Yes, you are in a sense operating as a test pilot once you venture above that number but as long as the rest of the paperwork doesn't say anything that converts it into a hard limit, you're able to legally operate in some serious crosswind conditions if you so desire. In the end it is up to you as a pilot to make the decision whether to land or divert to another, better placed, runway. The max demonstrated value in the books should at that point be a serious warning but if you are familiar with the aircraft and your own personal limits then the responsibility is yours to make that call.