My guess is money.. The 6i is about $100 cheaper now, so you either buy the really basic (like I did) or you get the better version and pay for it..

Have to say honestly had I known this ahead of time I probably would have bought the 6i anyhow since I personally have the right gear to set it up right, and 6 channels is all I will need for a while. (I fly on a tight budget, only reason Ive bought so many new gadgets recently is its my once a year from my bonus, and the "Economic Stimulus" check.)

However, knowing what I know now if asked I would definitely recommend the 7i if you can afford it, it appears to be a better radio all around.