This is nothing new, look at how many games used the quake 2 engine, for example.

The whole reason that people license the engine is so that they do not have to spend the time/money on that aspect of the game. Instead, they can spend more time on the story as well as any other little features and larger modifications that give that game its uniqueness.

I'd rather see games built around a solid engine, instead of games built around a shoddy one, quickly produced because of time/money constraints.