Basically, based on survey results, boomers and gen-Xers think workplace diversity is "the right thing to do to achieve compliance and equality, regardless of whether it benefits the business."
Millennials go beyond that. They define diversity as "the blending of different backgrounds, experiences, and perspectives within a team." That is, diversity isn't just important for its own sake, it's important because it leads to 'cognitive diversity' (i.e. diversity of thought). And this cognitive diversity is essential to "overcome challenges and achieve business goals."
So they don't just want to have diversity, they want to use it do a better job. And they're currently feeling constrained because, in many organisations, they have to be a little less diverse (they're required to conform more than they'd like) and, therefore, they're less authentic at work and less creative at their jobs.