Aquiles: Well it's easy. If you want an answer you speak a language that everybody (or at least as many people as possible) can read. And by convention, it's English, whether you like it or not. It's not a matter of being arrogant Northern Americans or whatever, most of us here are not native English speakers. But we do the effort, because we want our questions and answers to be used for as many people as possible.
Just imagine for one instant if everyone would ask questions in their native language here. Out of 10 questions, you'd have one in English, one in Spanish, one in French, Russian, Chinese, Greek, Swahili, Portuguese, Hindi... and well maybe a second one in Spanish. This Q&A would become utterly useless, as it would be hard to find questions that you can understand, and even harder to find the ones that you can answer (as usually one can't answer all technical questions). Same thing for looking up answers...
Now, feel free to setup a Q&A instance for Spanish speakers, where the rule will be to ask questions in Spanish.