Okay, I admit I am not an expert on cord blood!
But I have read a few things about how individual cord blood banking is controversial. Why? Because the cord blood banking companies prey on parent's fears in order to make a TON of money but in actuality, the odds that a family will ever need the cord blood they bank is very very slim. (not saying it would never be used, because it is occasionally, but it is extremely unlikely). Not only are the disorders that would require a cord blood transplant themselves unlikely, but also often there is not a good "match" (i.e., one of your kids gets sick but the blood you stored from your other kid doesn't match because of blood type issues).
Now, what goes along with this controversy is that people who are against it do feel that there should be a *national* cord bank. Basically, the idea would be that everybody who wants to participate could donate their baby's cord blood for free, and then if any of their family members ever needed cord blood, they could search the database and see if there was a match (it could be their own baby's blood or someone else's. Then if they never needed it, it could go to someone else who needs it, therefore helping so many people) Edited to add: to my knowledge this national banking doesn't exist right now, though there are ways to donate the blood for research and other stuf.
The argument is that when people privately bank the cord blood, their blood is probably going to be thrown out and never benefit anyone, (and they get gouged a lot of money), but if it were national, a ton of people could be helped.
Anyway, I am not really personally weighing in here -- I'm just giving the arguments that I've read. It is pretty interesting stuff!