Sofia,
I don’t get the impression it's like betraying one`s roots, it`s more like Spanish native speakers here, I think, just really love their language. To them it´s just the “normal” way to speak. And that`s a very natural human phenomenon thoughout the world, especially for people coming from developing countries.
The utility of learning English for them here is abundant, as well as the opportunities, but the more we accomodate them, the less likely they`ll be motivated to learn. It`s a shame really. I know if I moved suddenly to Peru, for example, the first thing I`d do is enroll in a Spanish language class because it would make my life so much easier. I wouldn’t want to go around hoping everyone would speak Engish to me.