I don't think you can get rid of it. The subtle crinkle look seems to be a side effect of pot-dyeing when the fabric just doesn't have enough room to properly swim around.
I've pot-dyed silk many times now using the Jacquard Acid Dyes, and whenever I dye copious yardage, I get that effect too. I dye in a huge tamale pot, the biggest I could find, but when dyeing more than a couple yards the fabric has a tendency to twist on itself and wrap around itself tightly while I stir. The twisting and wrapping is what creates the crinkle look because it traps dye in certain areas, exposing them to a stronger concentration of pigment. When I only dyed smaller pieces, or a yard or two of fabric, the twisting did not happen and I got totally solid, even color.
In my case, the crinkling was a welcome surprise because it made an appropriate visual effect for that specific project. But in other cases, I would have been really bummed out.
However, the crinkling may be subtle enough that it doesn't even show up in photos. I honestly didn't notice it in yours until I really paid attention and looked for it.
FF9 cosplay? Hit me up!
2014: Anime Los Angeles, Anime Conji, and whatever else falls into my lap
I now have a Tumblr
. Sometimes I use it.