Let's clear this up....
...get your prejudices out of the way first, becuase you may want MS to lose (for whatever reason), but these sort of suits could also apply to anyone else.
1. Microsoft are not trying to avoid paying license fee
2. Interdigital are not pure trolls, the do actual R&D. They may not make anything, but neither do ARM.
The issue is Interdigital's business practice of doing bundles that means you can't just pick the essentail licenses you need that would be covered by FRAND, but also force you to buy non-essential licenses you don't need, for which they can charge whatever they want.
This sort of business practice affects not just MS, but everyone.
So using everyones favourite analogy, cars. Any company is free to use an engine in their cars, but in order to do so, you have to buy a garden shed for everyone bought and if you make less than a million cars a year, you also have to buy dinghy.