I dont really think its hundreds of games for Gamebryo, I know of about 30 titles and many of those use 10.2 instead of the latest and greatest because I think it was cheaper to license if there was a preexisting contract with NetImmerse. While it does cost a lot to license it on the order of many hundred thousands of dollars for a AAA title if I recall correctly for the latest engine that would be spread out over 3-5 years for the average game.
That is not really that much money when you consider the amount of staff they probably had to keep for management, sales, bug fixing and new development. I think they got a lot of good mileage out of the engine but it really did need a substantial redesign I think and has to compete against Unity and Ogre and the like on the low cost side and Unreal and Id on the high end.
Edit: Guess I should have actually read the article first. It does say 300 games but I would guess most of those were not AAA titles commanding the full price of the engine. Zoo Tycoon and Pro Cycling Manager were not sold in stores that I remember.