I agree. My grandparents, then parents, then brother all had parakeets/cockatiels growing up. They didn't have pellet foods back then and they ate just bags of bird seed and all the birds were healthy, happy and fine. Never once went to the vets. Their food consumption/nutrition is only seeds/grain in the wild and in large outdoor aviaries, they don't invade people's gardens, they don't eat chemical/processed food when they're too lazy to forage, so why wouldn't you give them what they're Natural born habitat gives them to survive. I don't understand why vets say that their natural food selection is considered to be like eating junk food, that doesn't make sense? I can't help but think that the pellet pushing industry is much like the junk dog food industry....
I'm also coming to realize that my budgie is just as moody as I am, sullen and sleepy when the weather is lousy and happy and playful when the sun is coming in. Some days constantly foraging and some days just wants to rest. Seems like she's just like me and my dog when it comes to the behavior changes so I'm not expecting her to be the same every day, all the time as she grows.