The problem with Iconiq's Ryu is that the typical "museum pose" is not the
cast pose. The exaggerated size of his ribcage muscles (the serratus and dorsal muscles) means he was cast with his arms at a 45 degree angle, rather than closer to an arms-at-side position, because there simply isn't space under his arms to cast the figure in a "neutral" arm position. This means that a "neutral" pose with this figure is actually pulling against the material's naturally cast shape, and that's why you get tears like this.
This figure's "natural" pose would be something more like this:
View attachment 726203
These silicone bodies will always try to revert back to their cast shape, and when the internal skeleton prevents that, that's the main contributing factor to these kinds of tears. Heat and moisture (which causes shrinking and expansion of the material) only contribute to this root issue (by causing the material to stretch). Dye from untreated clothing seaping into material will also contribute long-term to damaging the flexibility of the material (as it causes expansion, too).
Don't believe any of the marketing fluff, there does not yet exist a silicone-based material that won't have these problems. The level of variability between individual casts and the environment they're kept in means some people will get lucky and have their figures in dynamic poses for long periods of time without seeing any external damage, and others might see cracks pop up in figures they treated gingerly, but it's all anecdotal and does not refute the basic physical chemical structure of the material. Any pose that is not the cast pose necessarily requires stretching the material.
To my end, I massively prefer having a figure with replaceable arms, and any time a figure comes with both jointed and seamless arms I wind up mixing them to attain my desired pose. My Zack has one jointed arm bent and holding his sword and one seamless arm held loosely at his side. I dislike that GT has moved to full seamless bodies. The only reason Zack's arms pop out "easily" when compared to Hot Toys's figures is that Zack was designed so that you could pop his arms out. That's why he shipped with a pair of jointed arms. Hot Toys are stingy and have never shipped a second set of arms with their figures.