Need to, or do you want them to?
Because althought some small things in the color variations need work. As far as I'm concerned, they should no longer invest time into adding more and focus on other aspects of the game and have more time to maybe make bigger DLC packs.
It's...not a matter of want them to. The hyenas look literally nothing like an actual hyena. They're spotty, and slope-backed, and that's about where the similarities end. The snouts are too long and thin, the bodies are very lanky where actual hyenas are actually quite muscular (and rotund after eating), and the tails of the cubs are way too fuzzy.
I'm happy with the colors though, and find their categorization into subtle differences as laughable.
In keeping with the thread, here's generation 2 of my color experiments with the hyenas.
This is one of the cubs from my previous post all grown up and now a mama. Because of how the game works, she's described as gray furred even though she's not.
Here's her boyfriend, a The Lion King lookalike just like the mother was.
And here's one of the cubs, a testament to just how much variation this new system actually has to offer in spite of everyone's protestations. She is very clearly too gray to be colored like mom, and yet is not close to gray enough to look like dad, though definitely resembles the father a bit more.
I think people haven't given this system its due because they haven't tried mixing and matching pairings of animals properly, or have just been trying to breed the wrong ones. I'm not gonna say it doesn't need to be refined further; it's true that some species don't have the variation they would have in real life, like the chocolate brown and black wolves, and some species need something more than just color variation: Color and size of manes or size of tusks/horns for example.
But the system we have is not bad by any means. People just gotta experiment.