I have a feeling that urahara and isshin were preparing on giving Ichigo's powers back anyways by sac-ing the "mystery" shinigami (I bet it's Rukia)
Spoiler
I think doing it the fullbring way is better though, because iirc they mentioned when he gets his powers back, he also is able to use fullbring, so he can absorb other fullbring abilities or something (relieve them of their "curse") and be 100x more powerful.