After a lot of visits to the store and a lot of over-analyzing, I decided against ordering a MacBook. I didn't want to order one on day 1 and return it -- I've returned other Macs that way and really hate doing it.
What finally did me in was mimicking the effective resolution (1152 x 720) on my 15" rMBP and seeing what it's like to use all the Adobe apps. Even with all the elements much larger on the 15" screen than they would be on 12", I just felt cramped. Of course I could bump it up, but then you're really getting tiny on the 12" screen and missing out on enjoying the retina display. I guess I've been spoiled by the 15" size. Fortunately I don't have to travel much, but even if I did, I think using Photoshop and After Effects on a quad core 15" display with 16 GB of RAM, when sitting for more than an hour at a time, outweighs shedding a couple pounds. I really wanted to like it, though. I even have a retina iMac and still feel that way with it as a secondary machine. That's my advice for most Adobe users, unless you're a photographer in the field or something like that. I get that it's comfortable to whip out on the couch and browse the web, but I think the iPad is ideal for that. Glad I've figured out my arsenal and all my use cases!
if you never used 12 incher, then it will be a huge adjustment for you... I've had x200 from Lenovo from years ago, so It's not a huge transition from 15 inch rmpb (in fact, it's an easier transition from that than from 15 retina to non-retina 13 mba)
but I agree with you. unless you really need one, I think Apple will come out with bigger version of thin-retina line. (it's stupid not to)