If it's any consolation, I don't think that the prevalence of English will threaten French, Italian or other national languages any time soon.

What I find interesting is that foreign words in English sound perfectly fine to me. In fact, I see non-English words as an enrichment of the English language. I suppose that French speakers and Italian speakers see English words in a similar light — as an enrichment of their languages. But I think that English is especially good at adopting foreign words because it's such a mongrel language with linguistic influences from everywhere.

And yeah, I definitely agree that you can only really understand a culture when you speak the language of its people. There's just a certain intimacy that you can feel when you speak someone's native language, and it gets lost in translation when you communicate with them in a second language.