That is an interesting question, although I am fairly certain that Hasbro legal is fully aware of their rights under the Sherman Act (I could be wrong however).
In respect to the Microsoft Case, Microsoft was in violation of the Sharman Act because OEMs were forced to purchase new licences for DOS/Windows for each hardware product they released, and for the fact that said hardware is not a derivitive product of either DOS or Windows.
In order to show clearly why Microsoft was in breach of the Sherman Act, I will use the following analogue.
Lets say I create a product, we will call it Peanut Butter, and (for purposes of this example), lets say I hold the legal copyright for all peanut butter products. For the purposes of this analogy, peanut butter is a direct analogue to Windows.
Another company makes bread for a living. Again, bread is a direct analogue to the personal computer for the purposes of this analogy.
Now, Bread just isnt the same dry as it is with Peanut butter, and many of bread-makers consumers prefer to eat their bread with peanut butter over another similar product (eg: Strawberry Jam, which could be analogue to Apple or Linux).
If I decided to create a limited licence for peanut butter, which forced bread-making companies to purchase a new peanut butter licence for each version of "Bread" that they produce (flax-seed, whole wheat, white, multi-grain, etc), I would be in clear violation of the Sherman act in the same way that Microsoft was, because the creation of Flax-Seed or Multi-Grain Bread is in no way a byproduct of peanut butter.
The key distinction here is the fact that all products using the OGL are considered derivitive works, simply by virtue of having used the licence. They are not considered stand-alone products in the same way that a PC is a stand-alone product from an OS.
PCs can just as easily run Linux/Unix as they can run Windows or DOS. Therefore, how can a PC be considered a derivitive of Windows or DOS? More to the point, Windows, DOS and all other Operating Systems are derivative of Machine Language, and Binary.
If Microsoft had designed Machine Language or Binary, then they would have had the legal right to place limitations on every product which was a derivitive of machine language/binary, but not on hardware itself. Microsoft was in breach because they were placing sanctions on hardware, and as a result, were placing sanctions on products which had no direct relationship to Windows/DOS other than by virtue of those two OSs being the most popular, and therefore wide-spread.
Im no lawyer, but thats how I interpret the Sharman Act in this situation.