‘International English’ used by non-native speakers is destroying the English language

My sister once said that she hates English language because it’s simple and stupid. The fact is that she lived in America for 5 years and is acquainted only with American or non-native speaking English. English is the second language for her as for the many other people on Earth with whom she’d been talking to. I strongly disagree with her. English language is really rich in vocabulary, so considering it stupid is nonsense! 

People who learn English just to talk to others, during their vacation in Turkey and stuff like that, don’t need any rare (I mean word that aren’t used often) words. They speak in a simple way because they lack extraordinary vocabulary that they don’t even need. Pretty often their goal is to uphold the pleasant conversation and that’s it. 

I don’t think that my sister is the only one who thinks that way. And this is frustrating that English is considered to be simple and stupid.