A pretty interesting discussion.
Personally, I think to fully understand the power of the German language (
or maybe even of any language) we have to take a look at poetry or music.
To combine both I'd like to recommend a few tracks in German I like a lot, and even if you maybe don't like hiphop/rap (
I myself like just a few sophisticated artists) you should give it a try and simply listen - for the sake of the impressive mastery of the German language.
HipHop/Rap
Geutz - Taugenichts
RuhrpottAG(RAG) - Kreuzwortfeuer
Too Strong - Die Deiche brechen
Wisdom&Slime - Das Element (Austria)
Punk
Wohlstandskinder - Das Grau unserer Zeit
Fliehende Stürme - Gestern
Baffdecks - Paul ist tot (Fehlfarben cover)
Captain PlanET - Rambo
Poetry
Hermann Hesse - Stufen (read by Hesse himself in 1949)
Gottfried Benn - Blinddarm
Rainer Maria Rilke - Nachtgedanken
Friedrich Nietzsche - Ohne Neid (read by Klaus Kinski - formidable)
I'm pretty sure that no language sounds rough or angry by nature. If anyone wants to transmit anger in his message he will use harsh words and pronounce them appropriately.
What I try to lineout is that German bears some potential due to its grammatical certainty in some cases, which I really like, and miss in English for example.
IMO to say German sounds angry or harsh is just too easy and superficial. I for one agree to one of my previous speakers here and say... it's
romantic and the more the language itself and its user originates from the early 1900s (or even earlier) the more impressive appears its very special, magical, maybe somewhat antiquated sound.