It's just business.
Perhaps, the late great Gygax cut TLG too many slacks, or have gotten too personal with the company to overlook what they did to his Castle Zagyg franchise. If it is in Gail and Gygax estate's interest to find better professionals to license the franchise, then so be it.
TLG should consider this as a wake-up call to improve their own business model, IMHO. It should also be a wake-up call for all RPG industry despite hard economic times.