Diversity of experience and backgruond is good. It brings differnet points of view and differnet ways of thinking about problems. It can also equip you with a wider range of skills han you otherwise may have on the team.
The downside of diversity is that the people are different. Often in projects we come together for one project, maybe two and then move on in different directions.
This means teams are alasy forming anew, building trust and modes of cummunication that suit them as a new group.
And this means conflict as norms and values are formed. (You remember forming, storming, norming and performing, right?)
Is the benefit of diversity worth the cost of reforming teams? It probably depends on the situation, but in most cases the answer appears to be yes.
Take a look at this aper from Harvard's Huckman and Staats;