Does WOTC ever play the 'loss leader' card with their products?
I don't know that WotC has any incentive to have a loss leader. Loss leaders in retail, as a small business owner, are used to get people in the door. You than expect that customer to purchase other items that have a higher margin to make up the difference. For a small business, I need a certain percentage margin to make my bills. Below that margin percentage my business slowly, or quickly, dies. Loss leaders lower that margin if unsuccessful in the above goal.
We can think of it this way. If I sell a product at a profit of $1, I make $10 if I sell 10. If I put that product at a price where I make 50 cents, I need to sell twice as many to make the same raw dollar amount. I'd be working harder for the same money in this comparison. This complicates the math on a loss leader, as it works the same with two items. If I sell two items for a profit of $2, and drop one to a loss leader at $0 profit. I'm selling the second one at cost. To make that make sense, financially, I need to sell twice as many of the first, profitable, item.
This is a gross oversimplification. But it illustrates why WotC may choose to not engage in that strategy. If they make $1 per starter set, just for illustration purposes, and $1 on each core book. And they loss leader the starter set to below cost at -$1 raw profit. They than have to increase the combined sales of the three core books by twice the amount of starter sets sold to just break even.
In this case they may take a break even for the increased customer base. But the decision is ultimately on whether there is enough potential customers or sales to be gained on other products to offset the cost of the loss leader. And that increase has to be a result of the loss leader. If the calculation is that most people will buy it at normal retail, or that the market is not likely to grow, they simply would have no reason to take the risk of making the starter set a loss leader.
I don't know that loss leaders make sense for WotC in this industry. They seem like they would be unlikely to see a rise in sales large enough to off set the cost. But that is a non-expert opinion as my small store doesn't compare to their billion dollar company.
EDIT: This is even harder if you are selling through partners, as those partners may choose to take the extra margin negating any real world effects of your loss leader. Meaning you'd just be burning money for, likely, no sales gain.