It could be a matter of the print run dictating the distribution rather than the other way around.
WotC Planner: "How many copies of MME do we expect to sell?"
Data Dude: "Trending factors says 7,000. With this kind of product, many will just get the info from DDi"
WotC Planner: "If we go with normal release, how many do we have to print?"
Data Dude: "Amazon wants to order 10,000 for the stores and online. They'll sell 3000, but we don't get a shelf presence for anything under 10K. With everyone else factored in, we'd have to print 25,000 to meet initial ship-out."
WotC: "What if we just hit the hobby trade on this one?"
Data Dude: "We could print 8,000 and probably see only 10% as fulfillment stock..."
WotC: "Sounds like the plan..."
OR - "Wow, after Borders closes, our cashflow is tight. I don't know that we have the liquidity to pay for a print run of 50,000 right now... anyway to scale that back for the next six months...?"
of something like that.