The German "guy" is actually a robot (so he's not offended by having called him "unprofessional"), since German it's one of the voices which use text-to-speech and, not all languages comes very well when using a voice from one language, but configured to speak in another language, which is possible, but clearly not as good as if the same voice was instructed to speak in his own language.
Those synthetic voices are basically placeholders, which will be eventually replaced by real voices as soon as we get them, the important thing was to get the software support in.
But don't discount the fact (confirmed by the post from Airmaz1), that some users might even find funny hearing that kind of heavy accent...