In a sense, the best answer to this is that the main “pro” of having “minorities in the workplace” is that some members of minority groups work hard and do their jobs well. They are beneficial to their firms. The main “con” then, is that some members of minority groups lack the skill to do their work, the drive to do it, or both. They harm their firms. But the same is, of course, true of white people, some of whom are good workers and some of whom are not.
So, let us look at this question differently. Let us ask what the pros and cons of having a diverse workplace are. Here, there are two main pros. First, a firm that hires the most qualified candidates, regardless of race, is likely to do better than one that tries to hire only people from one race. The diverse firm will have a larger talent pool from which to choose. Second, a firm that hires a diverse workforce may end up with a workforce that has more varied ideas. It may have employees who do not all think the same way. This allows it to be more creative and flexible.
The main “con” of a diverse workplace is that it is possible that there will be racial and ethnic tensions. This is hopefully becoming less of a problem in our society, but it is still possible. This can reduce the level of camaraderie in a workplace. With camaraderie and morale lowered, it is likely that the firm’s productivity will be lowered as well.