On the one hand, I feel that positive discrimination is just as bad as the other kind and that its proponents are not thinking things through as clearly as they should.
On the other hand, board members are humans too. Given the choice, and whether consciously or unconsciously, they will typically elect people much like themselves, because that's the kind of person they can understand and relate to. It's an understandable human trait but it does perpetuate the status quo.
I do wish the focus was less on gender and more on diversity in general. We have sizable ethnic minorities in the Netherlands but they are quite underrepresented in upper management and I'm not sure it can be fully explained by the socioeconomic and education gap.