I agree, and I trust Brez & Co to know when to call up these guys. Unless there is a major injury, or someone is stinking up the place, I don't see a major urgency. Of course, some could argue, why wait for DHam to stink up the place and just give the more promising Campbell (or Mayer) the shot on day one, and they have a point. I can see both sides of the debate, and am not sure there is a clear answer.
To me, the added year of team control, for a cheap owner like ours, might end up tipping the balance to waiting on the kids. It's not a terribly long wait, and it's not like DHam/Romy, Duran-Rafaela-Abreu/Ref and others have not shown enough skills and promise to also deserve a slot on the 26 and playing time. (I did not list Grissom, on purpose. He needs to prove himself, first. IMO, he does not have a case against the kids or the others listed.
These kids will get their chance, when they are ready and the need is great enough.