Of course, one could say this was none of Ichigo's concern anyway. It just so happened he got involved into it. Why tell people about unnecessary information they don't need to know to get their job done? Personally, I think it is no coincidence Ichigo got targeted. Probability aside (how many shinigami do you know have actually lost their freaking powers in the first place?), if we assume it is no coincidence, then yeah, they ought to have told him.