Thank you TurnaboutVox, Richannes Wrahms, ArtMusic, isorhythm and Woodduck for your posts on Brahms!
I can't strong-arm anyone into liking Brahms, but it does seem fairly clear to me what he's doing in that song: he's establishing the tonic key with a brief piano introduction, and then the singer starts on the tonic key, same as Mozart or Schubert would do. What you're calling a seventh in the second bar, I think is the relative major. Root movement by thirds without preparation is one of Brahms' favorite devices. I wonder if that second bar made you expect something more harmonically adventurous than you got, and that's why you're disappointed?
I was also unsure whether to call it D major or a seventh in that 2nd bar because it's very ambiguous. But I think it's the bass line in that introduction that sounds most problematic to me. I
see what he's doing: he goes up the root minor triad, then happens to use the 5th as a crossing point to the mediant major (D major) in the right hand, and leaps up to D in the left hand both to emphasise (perhaps) the D major harmony as well as prepare for a descending figure...it all sounds good and perfectly fine on paper. But when I actually listen to how Brahms executed this, it sounds meager and unconvincing. The jump from F# to D in the left hand just sounds forced and makes me go, "Huh?!", a bit like that sudden rise of the 4th in the strings in the 1st symphony introduction. I think it's to do with the fact that the F# is not very well harmonically established in the first place, and neither is the D. Hmmmm...I might be on to something here!
[Please note, by the way, that I never do this sort of analysis in my head while listening to music, I don't judge the music this way. I don't listen to music and go: "So that was the development, we must be onto the recapitulation now". I just listen to the music and like it or not. This is just me trying to understand why I don't like it, and why others might like it. Note also that I've never studied musical analysis and am not familiar with all the musical terms out there so apologies if I'm not being as clear as I could be.]
Here's the slow movement of his horn trio:
Starting around 5:15, we go through C flat major, E flat major, C minor, F major, D minor, back to E flat. The texture is very spare and there are no dissonances or twisty chromatic lines; we just slip quietly from one key to the next. This is pure Brahms.
I listened to that excerpt and right off the bat I had a problem with 5:19. This sudden shift in texture and musical idea is almost like the piano introduction in the 2nd Piano Concerto, and leaves me lost and frustrated. Again, after analysing, I can see what he's doing: the chords go like VI-V-I (Cb, Bb, Eb), and that chord progression can be found all over the Classical and Romantic repetoire. But again, the execution sounds all wrong. The piano does a descent, then is left hanging on the Bb. Not to mention that the bass line just before, again, doesn't sound very convincing to me.
EDIT: On more listenings I see that he seems to skip the Bb chord and jumps to Eb (as you wrote in your original post). It was the Bb in the piano bass which threw me off!
I did like the part from 5:20, especially the low C in the piano at around 5:30. But from 5:30 till 5:40, I've lost it again. It sounds like the performers have lost their place in the sheet music and the pianist is improvising some sort of pretty melody to cover it up. It is certainly a spare texture but...how can I say it, it feels to me like it's always meant to be going somewhere else, maybe to an even sparser texture or thicker texture, but Brahms keeps twisting my expectations around in a very unassuming and uncalled-for way which leaves me confused and frustrated.
As you can see, I can go on like this for pages and pages.....
a sense that the music is too deliberately put together. I think his striving after a Classical ideal was occasionally at odds with his Romantic impulses
I think I can relate to this. I've heard about the 'rivalry' between Wagner and Brahms (or was it Wagnerians and Brahmsians?), that Brahms was more conservative whereas Wagner was more progressive (guess which one I prefer). Perhaps I'm just not used to listening to Romantic music which hearkens back to the Classical era; my tastes are mainly late Romantic/early 20th century. I don't actively go out to listen to Beethoven or Mozart as much but I certainly enjoy their music as well. Perhaps the reason why Brahms sits in this "uncanny valley" for me is that his music attempts at connecting the two periods somehow and I just don't understand that style. It creates a sense of "restraint" in his music.