I think there are some pluses and minuses, much like with most of life.
Location: I think it is appropriate that Disneyland get another runDisney event. Adding another endurance event will make it less disproportionate.
Scheduling: The Tinkerbell ½ is three weeks after Marathon Weekend and four weeks before the Princess ½. It makes the first two months of the year extremely top heavy with events.

Some people need a period of recovery time, which if they were able to participate in these event it would not afford them.

It also means coughing up a ton of cash and vacation time in a short period of time.
Theme: I think they wanted as close to another Princess race as possible, as it seems to be quite popular. I feel a lack of creativity and drive to create a new product, much the way Disney merchandising has gone.
Female Focused: Half marathons have seemed to get more people motivated to get up off their collective duffs.

It seems far more achievable than a full marathon and training can be fit in with life's chores. The data seems to show that most participants in runDisney ½ marathons are women. From a sales aspect, I believe women are more likely to purchase souvenirs and memorabilia; so it would make sense that Disney stands to profit more from women than from men. (I apologize for the generalization, but stand in the Emporium/Mouse Gears/etc. and watch the registers.)
I feel that runDisney is trying to clone the success they have had with the Princess ½ only on the west coast.

I didn't like the way runDisney made me feel illegitimate in February, nor the attitude/comments I received from some lady runners on the course (not the majority--but still disheartening and rude). I am disappointed that Disney is seeking something to be less egalitarian and more exclusionary.

Since runDisney wants to focus on specific groups, I wonder how long until I get a race geared toward diabetic, gay, pudgy, slow guys?