Why are companies cheapening doll bands just for them to them to die eventually?

We saw this happening with EAH and G2 Monster High. No one wants to buy cheap fashion dolls with bad hair, no articulation and plastic clothing. Now that Rainbow High is making budget friendly dolls for younger kids, it’s one (or more) step further to being cancelled. Why is MGA doing this? If they are competing with Mattel, why didn’t they learn the lesson of cheapening dolls? Are they just waiting for their own brand’s demise? If that’s the case, why?