The pigs want to inspire loyalty and obedience in their followers—as well as iron discipline—instead of bravery. They say that bravery isn't enough because they know that if an animal chooses to be brave, then they might question the leadership of the pigs. Animals who have the discipline to stay loyal and obedient are less likely to turn against their leaders.
When the other animals are discussing Snowball and what he did at the Battle of the Cowshed, Squealer explains that his successes were probably untrue and exaggerated. When another animal declares him brave, Squealer explains that they don't put value in bravery. Instead, they value loyalty, obedience, and iron discipline.
These qualities are what enable Napoleon to completely take over the farm and remove Snowball from power. They let him change the commandments, sell the hen's eggs, and send Boxer to the glue factory. When animals choose not to remain loyal, they are defeated by Napoleon's forces and then convinced via gaslighting that Napoleon is doing the right thing. They're told that the rules haven't been changed; for example, instead of saying animals won't drink alcohol, the commandment really said that they wouldn't drink alcohol to excess.
Their loyalty and obedience are the qualities that keep the animals following Napoleon and the other pigs. If they were braver, there's a chance they might have stopped him before he turned Animal Farm into Manor Farm once again. Napoleon realized the whole time that this was the case and so cultivated loyalty and obedience.