But your score includes mistakes that you make! Is a space not a mistake? Is it not a key that you need to press? When it skips to the next word, it's quite non-intuitive to not put a space first.

If you don't press space, you're violating the idea of words. If you press space, the sentence you've constructed in your head is broken. Either way, it slows me down and frustrates me too much to play :)