Why is "O Fortuna" so bombastic?

Bombastic means ‘inflated’ or ‘grandiose’ or other words which imply a lack of substantial meaning. Whereas ‘O Fortuna’ makes you quake in your boots at the shear mind boggling randomness of all human life. It’s about the wheel of fate - one minute you’re down and the next you’re the commander of all you survey. And vice versa. It’s LIFE! It’s all that you feel when you’re alive expressed in a couple of chord changes.

Having said all this, I’ve often wondered whether it was just a random turn of the wheel of fate that made this music acceptable to us in the first place. It was being performed in late 30s Germany, and other parts of the piece feel quite ‘Springtime for … Germaneee’ (I mean the music and singing, not the words). Were there similar composers who are not performed now because they failed to distance themselves from the politics of the time as well as Orff did?

Well, not everything, even some parts of CB are quite gentle and delicate, but in his most known works at some point there is likely to be at least one passage where the notation at the start of the section is: *"&%#$ng Loud!". His last work, *De Temporum Fine Comoedia, * has some wild, acoustically scary passages, IIRC, where the effect is as much the very shrill vocals as any orchestral banging.