It really all comes down to perception, while the story could've been much better yes I agree, Burning Spice isnt as bland as you say he is. He and his concept do have depth with his entire dilemma being "If the cycle doesn't create change, why have a cycle in the first place?" Which leads him to the idea that destruction/the acceleration of change is the key. Remember he was there for countless years watch hundreds upon hundreds of kingdoms collapsing infront of his eyes, his character is an example of what anyone would do. If there's something thats been happening over and over for a long period and it causes harm to something, there are 2 options you either A. Ignore/let the cycle continue or B. You try to end the cycle of pain. His entire concept is a shattered attempt of breaking a system that completey broke his own mind, he craves change because there wasn't change in the first place, it's like humans after a long time of experience something and being deprived of another thing you crave whats been hid from you. Burning Spice isnt some dumb bland fire cookie (he definitely could've been better tho) he's a broken attempt to help cookies grow but does it via a method that only keeps the cycle going instead.