Board Thread:Questions and Answers/@comment-24963288-20190412183516/@comment-5171765-20190517114346

There is also the fact that Tite makes it up as he goes along depending on what he wants people to look like, as it affects how you think of them. Yamamoto being so old kind of has the effect of making you think, wow this guy is going to be some sort of master, but also set in his ways when we first see him but dont actually learn much about him. Rukia's and Ichigo's kids would not have had much impact if they were toddlers, so they had to reach that age at least.