Why Xsalsa20 instead of Chacha20

I wonder why the Crypt module uses Xsalsa20 instead of Chacha20. I’m not a crypto expert but when I’m not mistaken I read that it should be a little bit less secure than Chacha20. Is that true and why is crypt not using Chacha20?

The reason is that is what the NaCl secretbox format gives us.

I think this crypto stackexchage probably answers the why quite well!