The way I look at it, Disney needs to deliberately offer an "incentive" to people with kids to use their restaurants. I think people with kids are more likely to go offsite for dinner (perhaps looking for better deals), bring their own food (at places with kitchens like DVC) or just eat at CS places and not do sit-down places. With the
DDP child's deal, plus the added "incentive" of possibly being able to use some child's credits to greater advantage, families that come to WDW are much more likely to stay onsite ALL of the time and eat in their restaurants.
The dining plan and the Magic Your Way ticket set up are brilliant from their perspective. They get people for much longer stays because given the price steps, it is actually difficult NOT to justify a longer stay. They give you additional park days nearly for free (once you get past 4-5 days), and they sell you on a dining plan that captures ALL of your food dollars so you guarantee that seats will be filled at their restaurants and they know that you will never leave the property to give any dollars to their competitors. In return, they are offering everyone a "break" on price (the dining plan is a good deal if used correctly), and even more of a potential "break" to families with young kids - the most likely population to not eat at their nice restaurants.
For those "ethics police" on these boards, leaving aside the use of child credits, do you think that it is unethical to milk the DDP for more value than you actually pay per day? For example, if you did a lot of research you could find the absolute most expensive entrees available at CS locations and go to the TS restaurant that has the most expensive items available, just to maximize your "value". It is very possible, and probable, that if done that way, you will get foed for the day that is worth substantially more than the $37.99 you paid for the Dining Plan. Do you think that is "cheating Disney"?? Of course not! That is how the system is set up. That argument, to me, makes about as much sense as saying that people are unethical for using legitimately purchased child credits for adult meals if the child is not present or doesn't want to eat enough to justify his own child's meal at any given point, or even just in an effort to "maximize" value.