By "standard curriculum", are you referring to our base curriculum for non-black belt ranks? By Genbukan standards, that would be the base curriculum. Once you achieve shodan/black belt in Ninpo, it's similar to graduating high school. You're then off to university and you select a major. In the Genbukan, this can be continuing to grade up in Ninpo, or begin formally ranking up in Jujutsu, Koryu Karate, Chugoku Kenpo, Bikenjutsu, Bojutsu, Naginatajutsu, or any ryu ha such as Kukishinden Happo Bikenjutsu, Koto Ryu, Gyokko Ryu, Gikan Ryu, etc. So ultimately, there is really only one "standard curriculum" which is your white belt (10th kyu) to 3rd stripe brown belt (1st kyu). Under that context, the kata you learn from 10th-1st kyu require no such thing.
Beyond 1st kyu (e.g. shodan and up), that may change. While I am unaware of any formal requirement (except possibly in Amatsu Tatara) to associate elemental energy with kata, I do know that there is kuden (verbal transmission) associated with many kata. So while I would avoid saying it's a requirement, I would also say that by understanding the elements and being able to attribute them to kata, they can improve your techniques.
Example: You are doing a technique called "suisha". This means "water wheel". The root element in this technique is water. Your opponent attacks you and you receive that energy then redirect it back, ultimately throwing them backwards in a manner where you almost end up looking like a water wheel. Or maybe you are assuming a kamae (a.k.a. posture) which is very strong and defensive; this would be a kamae describing the earth. Wind can be attributed to quickness and evasiveness while fire can be attributed to directness and aggression (for the lack of a better word). Ultimately, the 5th being "void" (or "heaven") is being able to culminate all 4 together.
From a more non-physical perspective - if someone is angry with you (fire), you should avoid displaying anger back toward them because, well, obviously you can't fight fire with fire. It would be better to remain calm and redirect their energy into something more positive. This would be assuming the role of water.
Granted, the far majority of classes in Genbukan Ninpo won't entail any discussions such as these. What I explained is a VERY rough and high level overview. There are very, very deep spiritual meanings behind this stuff and isn't taught to most people. Even then, that information probably wouldn't be shared with the public.
Apologies for the long winded answer. Wanted to try my best to answer based on my current knowledge.