The other day I posted a call for curricula (see here). I also think that this commits me to wanting to see more katas. Consider, for instance, affiliations and gyms that have a formal self-defense curriculum (e.g., the Valente Brothers, Royce Gracie, Relson Gracie, etc.). For self-defense, the method of demonstrating one's effectiveness often involves performing formal katas with an uke who plays the role of attacker. The more proficient you are at the katas, the better. There are lots of benefits to kata-based martial arts--which is presumably why so many rely on them. They help both the student and the instructor. They provide guidance to the student and they provide a standard for the instructor.
Yet, when people talk about jiu jitsu, one of the virtues that is often lauded is the fact that it doesn't rely on katas--rather, there is live rolling. Obviously, this, too, is true of other martial arts--e.g., wrestling, boxing, muay thai, etc. But that is neither here nor there for present purposes. What I wanted to point out for now is simply that by developing a curriculum and doing testing for belts, one essentially imports the kata-based format of more traditional martial arts. While live rolling will still play an important role, so will the ability to perform (and perhaps even explain or teach) a particular set of katas. These katas will range from cross collar chokes for white belts to heel hooks for upper belts.
Once students know what the katas are, they know precisely what it is they need to be able to do. The hard part is settling on the set of katas that you want to require of students. After all, jiu jitsu is too expansive to require complete expertise at all facets of the art. So, settling on some facets--or katas, to stick with the current language I am using--is going to be a necessity. It is perhaps this difficulty that prevents instructors from developing kata-based curriculum. Where do you even start? My answer: On the feet! But I am biased of course. To quote a brown belt I met recently, "you should have to earn your way to the ground." I agree. Luckily, take downs can be broken down into katas as well!