"Fairness" as you use it should have no part in a business decision. The Microsoft HR team identified that for them to maximize their competitiveness (i.e. profit), they need more female staff members. That means that an "underqualified" woman suddenly becomes more qualified because she brings a business advantage to the table that a man does not. I have no problem with this.
1. Microsoft does not make decisions (mostly) based on fairness to prospective employees. It DOES make decisions based on having a good public image, part of which is being seen as diverse and inclusive.
2. The reason being diverse and inclusive is seen as good is because of a ton of research showing that being diverse is good for companies, good for employees, and good for entire underrepresented communities.
So it's not fine, but the fineness or not does not exist in a vacuum. The two situations are not arbitrary, and therefore, not analogous.