I heard that most of the Niman specialists on the first Battle of Geonosis died in the arena. Why is it that they couldn't train more? Apparently it's idea is to have everything in moderation. If one trained enough, then the form could probably turn from good at everything to awesome at everything. You might not have as much precision as Makashi, or speed as Ataru, etc., but you'd have no apparent or major weaknesses and a very well rounded strength.
Because Niman is a style for Jedi who don’t focus on combat
Niman was generally used by Jedi whose primary focus was not combat.
Niman, also called the Moderation Form and the way of the Rancor, is the sixth traditional lightsaber form. In everyday parlance it is known as the “diplomat’s form,” for it is the preferred style of Jedi Consulars who have not chosen to make a career out of combat.
The Jedi Path: A Manual for Students of the Force
This is likely because it was often considered easier to learn than other styles. The downside of this, of course, is that it is useful in combat than some of the other forms. Regardless, those who practiced Form VI were often those with less time to devote to lightsaber training.
I assume the question is referencing this bit of information, which renders the matter more confusing:
The predominant, “standard” form common in the prequel era, it balances the emphases of the other forms with overall moderation, in keeping with the Jedi quest for peace and balance. It is considered the “diplomat’s form,” as it is less intensive in training requirements, allowing a Jedi to concentration on other arts of negotiation. In practice, Form VI is a combination and distillation of Forms I, III, IV and V. In earlier years, young Jedi would study Form I for a few years, and then devote a year or two to the study of III, IV and V. Form VI, by contrast, requires ten years of study after Form I. While its advocates point to the fact that it includes elements of the other forms, it detractors feel that ten years is insufficiently demanding given the end results: almost all the Jedi at the Geonosis arena who favored Form VI were killed. It was also known as the Way of the Rancor and the Moderation Form.
While this confirms that Form VI is less “intensive” than other forms, and thus preferred by non-combat Jedi, it also asserts that it requires five to ten times as much time as the other styles. The most likely implication seems to be that it spreads out the training over a longer period, providing more time for other activities. So, again, those who practice Niman are often those with the least time to train.
Because Niman is not an unbeatable style
First, it’s important to understand that Form VI, or Niman, is a style of its own that incorporates elements of other styles, not simply incomplete mastery of those other styles. Mastering the elements of Niman to their fullest extent, then, does not imply complete mastery of the other styles, or even necessarily reasonable skill therein. There are elements of other lightsaber styles that are simply left out of Niman.
The essential thing to grasp, though, is that each style has its benefits and drawbacks:
- Some styles are better against certain opponents than others (for example, Form V, which focuses on deflecting blaster fire, is particularly well suited to droid armies).
- Some styles are more suited to certain Jedi than others, and thus they’ll find it easier to learn those styles, regardless of the style’s advantages or disadvantages.
- Some styles are simply easier than others, such as Form VI. As such, people will be more likely to learn them, even if their overall utility is lower.
This is, of course, why there are multiple lightsaber styles to begin with.
For example, Mace Windu was a master of Vaapad. As such, he was presumably not as good at redirecting blaster bolts as a Jedi similarly skilled at Shien, and thus not as good in combat against massive droid armies (though still quite good, of course). However, its unique strengths made it highly useful against the Dark Side, and thus Windu could stand against Sith Lords who would easily kill a Makeshi or Soresu practioner of the same general level of training and Force strength.
Quite simply, it’s not correct to say that a highly-trained Niman practitioner has no weaknesses. Their weakness is that they won’t be as good at various aspects of lightsaber combat as masters of the other styles. It’s basically a trade-off between "easy to learn" or "flexible" and "powerful":
While it is true that it would be nearly impossible for a Form VI adherent to defeat an expert in Makashi….
The Jedi Path: A Manual for Students of the Force
Again, while Form VI has elements of other styles, that doesn’t mean that it is those forms. No matter how hard you train at Form VI, you’re still a Form VI master, not Form III master. Sure, it will be easier to pick up Form III if you have experience in Form VI, but there’s going to be a ceiling to how much you can learn.