If I'm missing some studio which has a diverse catalogue of consistently successful games, then please tell me which. But I feel they usually find a niche and then work that.
Was that pitched to them? Solicited to studios by them? In the latter case that would be a fascinating process to observe.
The point is that there must be a formula if studios can consistently deliver.
I hope some day to play grand theft spaceship, grand theft dragon, and maybe grand theft dinosaur.
Most will find a formula that works for a niche and stick with it. Which is smart because innovation increases both the chance of achieving something great and of releasing a fiasco.