Japanese are trying to speak English (;_;)
http://hayabusa.open2ch.net/test/read.cgi/news4vip/1405572139/

Oh, very easy. Because they want to use Japanese language for their emotion, simply reason.

It is quite OK, I've seen much worse examples of Engrish.

Because their mother tongue is Japanese. The same reason why foreigners cant speak Japanese.

Learning to make certain sounds comes easiest at a certain stage of childhood. Japanese lacks a bunch of sounds used in English so most Japanese people don't learn them early, and learning them later means more difficulty getting them right.