mostly it's because China is quite far from Europe and as for language -- Chinese is very easy

There's quite a lot of them, really. Not really so few. I guess languages taught in schools were dictated by likely use, languages used with major trading partners, travel destinations, similarity to mother tongue to suggest rapid learning, & such. That given, schools then have inertia to change with investment in place. Chinese is tonal. Tone changes meaning. Yes tonal languages can be tough for other speakers.