It's because they wanted an unknown Mexican from Chorpus Christi to play Selena (her home town), not some actress who's already famous from another country. It's the same with Abigail Breslen, who's going to come out on Broadway as Helen Keller, who's mute, blind, and deaf -- an organization for people that are mute, deaf and blind want a person like that to play Helen Keller, not an already famous person.
The producers really want to be sure they have a famous person so it can be a gauranteed box-office hit. But other people are trying to be politically correct about it.
