It's interesting to see how many people are so concerned with root, yet bought a device with a locked bootloader. Especially considering how readily available Motorola has made the developer editions...!
First, in the US very few people buy off contract phones given the carrier subsidies are built into their wireless service contracts. And the Motorola Dev Eds (as is true of all Dev Eds) are only available off contract. So if you go with a Dev Ed, you are paying for a subsidy but not using it. Of course, you can buy an iPhone with your subsidized upgrade and sell it, but many people aren't willing to do this or don't know how to do this or are afraid of using craig's list/swappa/ebay to sell a phone. I know I was nervous the first time I did it.
Now things are beginning to change in that at least 3 of the major carriers are offering discounts on your bill if you will forego subsidized phone pricing, but for my carrier, to get a discount you have to enroll in their installment program and get the phone through them, and you can't get a Dev Ed through them. The discount does not equal the subsidy unless you are on a family plan using 10GB or more per month of data. But if you are, the discount exceeds the subsidy. So your best bet is to either stick with the subsidy built into your plan or go with Verizon's installment plan, but either way you can't get a Dev Ed.
Second, you can't customize the Dev Eds and while that may not be important to some people, a lot of people really like it. I bought a second Moto X just to get the wood back, lol! Not entirely true as I am going to use it for WiFi tether in my house as soon as I root it, but that wood back for only $25 extra sure was hard to resist.
So in the US with the subsidy and customization options, being readily available isn't the whole story.