Okay, first I will say that I am so sorry that your first Balenciaga bag has turned out less than satisfactory. It doesn't matter what anyone else thinks but you. You've paid quite a bit of money, and for you to be anything but thrilled with it, is not acceptable.
I personally prefer the older leather, mostly the 05 leather, which is thicker, smooshier, and has no veiny appearance. But I don't want it to look plastic like, I prefer it to have some personality.
My personal opinion of your bag is....I agree with you on it looking funky because one side is smooth and one side is wrinkly. That looks a little strange to me. I don't see the mark you mentioned but I do see the unevenness of the plate. If you bought it in a department store or Bal, NY and the paper tag says 2007 then it is definitely not an 06, and I have been hearing that the 07 leather is thicker, smooshier, and less veiny than 06 leather. Also, dryness in a bag is the least of your worries. If indeed you get and keep a bag that is dry, it can be easily remedied with many different lotions and/or leather conditioners.
Even if with use the look of the leather evens out, I don't think you should keep a bag that you have to wait to see if it becomes a bag you will love. You should love it the moment you get it! You mentioned being at the mercy of the store, so it is a store with a strict return policy? Even the stores with the strictest return policies will let customers do exchanges. I think with how it seems you feel about the bag, you should make an exchange. If you can't pick out a bag yourself, explain as thoroughly as possible your likes and dislikes regarding the bags. Also, with this bag having a few flaws, I don't think you should be responsible for any shipping costs! Please keep us posted, and good luck with whatever you choose to do!