I hear what you are saying but, they knew the DINC was still backordered since it was released in what April? These are one phone with one OS and they are on one carrier. So I'm not seeing your point. DINC / Dx / Storm I / Storm II were one device with only one possible OS and on one carrier so I think the logic is that they should have been able to avoid this problem.
If a company like Apple can make up the units they need for a launch then for crying out loud a company the size of Motorola should be able to as well.
Motorola would be taking a financial risks because of the potential for decreasing sales or lackluster initial release. Apple for example knows that there are billions of little Apple Lemmings out there and basically puts the company on the line for every Iphone release. Practically buying up stock of the next phones parts as soon as the first starts selling.
Motorola on the other hand develops a phone a year before it comes out. Relies on Google getting them a working OS. Develop their own software for it. Project competitive features of other phones both in their market and out. If Motorola, counted for the decreased interest of the phone outside the initial rush period, they would have to hold the phone for 4-7 months after production started just to have stock to make sure everyone who wants the phone has one. What would happen then? 4-7 Months from now HTC would have a 4.3" with Uni-body aluminum frame with a better UI. If they tried to rush the production they would have to retool lines for the Dx, produce a bunch, hire and lay-off workers between start and finish, and then retool the line. If they went with a just plain high output, they would have so much extra stock that the DX would be considered a failure and nothing like it would be made again.
The way almost all of these non Iphone releases are going to be the same. Design phone, Hold stock for 30-45 days after start of major production. Major production consists of lines projected to keep the phone in stock long term during its production period, and not the original rush period. If demand is heavy early then they will be mostly sold out. As those people get their phone demand drops off and supply~Demand. We saw the exact same thing happen with the DS, DSI, WII, X360, and any other big release not the PS3.