I don't know why they have raised the limits. But the Mexican social safety net is better than the US social safety net in some ways, medical in particular. There is also DIF*, but I am not familiar with the details about what they provide.…
As an aside - and I'm sure I'm not the only one to ask this question - why would the Mexican government make it more difficult for foreigners, especially retirees, to qualify for residency visas? Are they afraid of indigent gringos making demands on the almost non-existent Mexican social safety net?
*Desarollo Integral de la Familia