I agree that the best solution to people grabbing the same two Talents a lot is to have a larger number of good Talents so people naturally diversify. Missing are good Talents for all seven of the magic schools, as well as some other specializations for physical fighters.
However in this case, I think that making Warlord and Pawn mutually exclusive is not a terrible idea. It does help focus more on picking a Talent for a specific build. Although perhaps I just have a lingering grudge over the fact that Warriors can take both Warlord and Pawn easily, while Rogues cannot, being stuck with the Back-Stabber Talent Tax.
