If what you mean by recognizing diversity is what I call small 'd' diversity, I have no argument. If there weren't different people with different interests and abilities then an awful lot of great and necessary things would not get done. We couldn't even play baseball if everyone were a catcher. But if you mean, as has been said in various quarters, that our diversity makes us strong, then I am not so sure I can agree with you. I'm not convinced that diversity is a valid basis for our thoughts and actions.
What makes us strong as a nation and as individuals is an underlying unity which we all accept as the rock upon which society is built. What we bring to the table, so to speak, should be small-d diversity, innovations will help strengthen and improve that unity. It is only when we concede that diversity is a tool of that unity that we might make persons and societies better.
So if what you mean by diversity are things contrary to that unity, ideals which will harm or destroy the body politic or personal responsibility, then it is not something we should want. If by diversity we mean to accept and appreciate cannibals and cannibalism, then we should not celebrate it. Aristotle did not appreciate the barbarian hoards who raided northern Greece, nor should that have been expected of him.
I fear that many of the folks who wish us to celebrate diversity wish us to do just that: accept diversity as a guiding light, as a principle in itself rather than as a subject of unity. It is a hedgerow behind which folks sneak beliefs into our system which will hurt or kill it in the long run. It allows free play for ideas which will lower the individual into a mere animal. We are better off celebrating a positive, rational unity. It allows us to see what unites rather than divides, because in union their is strength. In capital-D diversity, we are just so many grains of sand, drifting into this or that form as the winds decide.