Ok, so if they can grow replacement bladders for people, then why stop there? Make the scaffolding bigger than my current bladder and use my genetic material to give me a bigger one! I could go hours without pointing the pink pistol at the porcelain firing range. Sure, it's good to replace parts in, say, your car when they break, but it's just as legitimate to upgrade your car too, right? Right? Wait, does genetic material hold information about size?
oh, man, think of it! Maybe a couple times you have to do an overhaul when your body hits 200,000 miles (or cheeseburgers) and get a new heart, liver, lungs, kidneys. Had your gall bladder out for stones? No problem, we'll order one from the factory. It'll be a couple days.
Of course, now we'll have to deal with unscrupulous body mechanics. "By the way, it looks like you could use a new spleen, and we recommend a full small intestine replacement every 20 years. Look, lady, if that goes you're going to be in for a lot more repairs."