I feel like these opinions are often far too restrictive as I often have to pick a side as I am more in the middle ground. First of all you use the word diversity improperly here, using it to mean racial diversity, however there are other forms of diversity that are good such as intellectual diversity. Different ideas are good because competing ideas force people to defend their position more. If everyone on earth agreed with one religion then we would have no reason to believe it other than because everyone else does. Now we have to think critically and choose for ourselves what we believe in.
Second point, multiculturalism can be good or bad depending on how its used. If we hire more black professors, but it turns out that they are better professors then it is good, but if we hire them only because they are black and they are worse than their white peers then it is bad.
Lastly, G0yim arguments and debates are good, I do not understand why you are associating a negative connotation to those ideas.
I believe diversity only separates us from each other and causes more arguments than help for each other.
Look at Christianity and Islam. You can never convince either side that one ideology is better than the other. This is an example of why I think we should try to stick with each other instead of vice versa.