If that were true then Ichigo's dad would never have regained his powers. You don't lose or sacrifice your power then suddenly get it back.

As for Ichigo's dad, I think he lost his powers because he was stripped of them when he chose to live with a human.

But the Final Getsuga Tenshou doesn't actually get rid of reitsu though. So that's doubtful.

The reason that Aizen cannot sence riatsu from Ichigo is that this is the true power of Ichigo's bankai; His bankai during the SS arc allowed him to compress his riatsu to increase his physical powers, however, because he gained his bankai so fast and his spiritual body was so young, he, like Toushiro Hitsugaya, had an immature bankai, now, it is his true bankai: a complete supression of his riatsu and a heavenly strength and speed, thus the name Heavenly Chian Slaying Moon.

The reason that Isshin was in a human body was that he probably used a Gigai that supresses riatsu, the kind Urahara made, because, eventually, you become a full-fledged human by wearing it too long, thus Urahara's apology for Isshin losing his shinigami powers. The reason that he used that kind of Gigai was that he would be able to meet with Ichigo's mom without attracting hollows to his vast riatsu that he would normally leak out.

Urahara would feel bad cuz he probably didn't know about how you lose your riatsu from the gigai and isshin got the short end of the stick because of it.

Isshin doesn't blame urahara cuz he didn't know about the downside; urahara apologized out of his own guilt.

well i heard about a hell arc.

Well, the Movie can hardly be worse than the manga at this point......