They could have printed the detail on with raised inks. Actual texture, they can put sculpted detailing onto fabric now, have you held any of the Spider-Man figures or Man of Steel? I think they could have done it amazingly TBH. One area that HT have really leaped forward in are these fabric, plastic/rubber imprinted suits. They look amazing as well IMO. Both Spider-Man, MOS and a couple of others have had detailing deeper and more defined than rivets?
The chest definition is almost there on MOS compared to this, but they could always have bonded the fabric to a sculpted chest piece inside.
Basically all I'm saying is that they didn't need to use rubber on this one. They even stopped doing one piece rubber on their Nolan bat figures. It's such a pity a ****ing cool figure like this has potential rubber concerns and articulation limitation.
By the way check out the Thor and Gamorra threads if you think HT don't have current rubber issues.