Whenever people are able to rely on coercion, authority and force as the basis of their social, economic or political power, the result is that aptitude more and more ceases to be a requirement to fill that role. Instead such roles are filled by people who can buy into the ready made seats of power, or who can gather enough thugs to seize power, or who brown-nose their way up the hierarchy. And, as such, the result of any system that relies on coercion and authority to enforce the power of certain set positions, is a tendency towards rule by idiots, incompetents, corruption and abuse of power.
So, if you want order, you need competence -- and fascism doesn't give you that, it gives you violently enforced idiocracy. If you want greatness and striving, again, fascism won't give you that -- it will give you corrupt fools abusing their power and stirring up fear of internal and external threats in order to hold on to their power, until their disastrous incompetence leads to society wide collapse from war or slow degeneration.
Furthermore, the concept of nationality is an inconsistent social construct that normally just serves the interests of rulers trying to find a way to manipulate the people they are ruling over. Cultural differences exist, and the rich diversity of our species should be celebrated -- but the mixing of cultures is one of the greatest ways to innovate from what we already have, and is something people have been doing since pre-history, and is the engine that produced the very cultures you wish to preserve.
And if humans are often group minded and irrational (which I agree with), then having one of creatures such as that have absolute power over others is not a solution to that problem.