There may need to be more than one shade of a colour, but having a large number of shades suggests to me that the design has too many subtle contrasts in brightness.
Regarding colour generally, I think it's a useful tool and it is nice that it's used more in certain respects than in the 90's, but I'm not convinced in general that “modern” design makes the best use of it. For example, use of more than one colour within UI icons has become uncool because it's less pretty, despite it making them harder to read and distinguish. Function has taken a backseat to æsthetics.
Regarding colour generally, I think it's a useful tool and it is nice that it's used more in certain respects than in the 90's, but I'm not convinced in general that “modern” design makes the best use of it. For example, use of more than one colour within UI icons has become uncool because it's less pretty, despite it making them harder to read and distinguish. Function has taken a backseat to æsthetics.