Rammstein is not all about controversial stuff. That's just a small part of them. Lindemann's lyrics are actually very intelligent and (this might piss you off) maybe it's not the same when you don't get all of the lyrics. They're full of images and onomatopoeia and words that are not usually used (anymore). I'm guessing it's very hard for a non-German native speaker to understand at times. Lindemann's plays on words are incredible, very well hidden at times and sometimes pretty hard to understand.
Even I had to google some words to understand them. In "Haifisch", Till uses the word "Zähre" which I had never head before. It's actually a synonym for "tear" from "Old High German" from around the 8th century and it's never used anymore. He sings more or less:
"The shark has tears, and they run down his face.
But the shark lives in the water, so the tears cannot be seen.
In the deep it gets lonely, so the one or the other tear ("Zähre") will run (?)
And that is why the water in the oceans is salty."
I don't know about you guys, but I find this very beautiful.
Lindemann adapts Goethe (the song "Dalai Lama", adaption from the Erlkönig (1782)), Kurt Weil ("Haifisch", an adaption of Mackie Messer from the Threepenny Opera (1928)) or Fontane ("Roter Sand" is inspired by Effi Briest (1895)), among many others.
I gotta admit, I am a huge fan of Rammstein (definitely in my top 10 bands of all time), so this post is probably not very objective. And I get that some people don't like them, but I'm actually getting a little tired of the fact that people think that they only do what they do to be controversial and to piss people off. Their music is also not dull and unmusical, because that's also just a small part of them. They are rockers, they are tough dudes, but they're also romantics. Lindemann has released two books of poems (!), for gods sakes.
Fun fact: My girlfriend (who loves Ed Sheeran and Rhianna) once had a big fight with her parents and I was there also. She stormed out and told me she just wanted to go somewhere in my car. She was super pissed and wanted to listen to something aggressive and loud. So I put on Rammstein. It totally calmed her down, she really started listening to the lyrics and melodies, and sometimes just had to admit that they have beautiful melodies and lyrical phrases that she never noticed, because she only knew Du Hast and Pussy. But if you listen so a song like "Nebel" (a song about an old couple in which she confesses to him that she knows she will die soon... hauntingly beautiful) or "Donaukinder" (a song about the Plague), you'll see that this band is more than just about controversial stuff and being tough and German and pissing off people.