I like the idea of having more natives civs in the game. However:
1- Mayas are already represented as a minor civ. Considering their Golden Age is long gone, I think this is fitting. (also they are in AOE2, so they are not completely out of the AOE universe)
2- Aztecs and Incas are not super popular to begin with, so I don’t see why it would be different with Mayas. I think redesigning some Natives features would be important before adding more civs.
3- There are still many important civs with ZERO representation in the game (ex. Persia, Oman, Poland) that could be more interesting as well as other Native that are way more unique than the Mayas and coming from areas with little representation as well (Tupi or Mapuche for exemple).
In this forum, there is a pool for most wanted natives civs. Mayans were not added, but mentioned there and there. [Overdue Poll: Most wanted Native American civ?] They dont seem to be a popular request in any case