Wiat I didnt know Gins clothes change too. Cool.
My favorite designs is either Ichigos or Kenseis. Kenseis is cool how he goes from pocket knife to giant metal gloves yet I still dont know what the purpose of the back was meant for. I likes Ichigos because when he moves he looks like some tricked out ghost.
No Gin's clothes don't change when he goes bankai unless I didn't notice it or something lol. I can't to see it in the anime though and Isshin fighting.
BTW The Bleach anime will have 2 episodes focused on the 4th Bleach movie.
Anyways I was doing some research over the week as to what the FGT really did to Ichigo and here is what I came up with.
My current theory on Ichigo's current powerless status.
Ichigo used FTG and lost all his reiatsu and powers, however since the same happened to his father who got his powers back over the years Ichigo can surely get back his powers. So here is what I think FTG did to Ichigo.
FTG closes up the Shinigami user's Saketsu and Hakusui due to the overload of power the Shinigami experiences.
In a Shinigami, the Saketsu acts as a boost to spiritual power, in conjunction with the Hakusui (魄睡, Soul Sleep), the source of spiritual power. These two points are commonly considered pressure points. If they are pierced, they seal up this spiritual power, and the Shinigami will lose all their power. The Shinigami who experiences this will never be a Shinigami again.
Over time the Saketsu and Hakusui opens up again slowly and then eventually the shinigami has his/her power again.
Interesting notes: Isshin lost his powers over 20 years ago and Ichigo was born 5 years after Isshin lost his powers give or take a few months depending on Ichigo's birthday and the day Isshin lost his powers. Also Isshin knew Kon was in Ichigo's body the very first time.