Sorry for the late reply.
I agree with your comment about the uncaptivating start. Maybe I should cut down the intro a bit? I'll see what I can do.
Your proposed reason for this problem I think is wrong because your assumption about the origin of this piece is false. I, in fact, did not decide one day to write a symphony in tragic sonata form. This piece is pretty much a polished and orchestrated piano improvisation, so "letting the form of the piece arise naturally and organically" is a given. This first part is especially (strucurally) very close to the original improv (the development is the most different I think).
And regarding your suggestion to write more shorter pieces, I do. I've got dozens of short pieces that I write solely to practice different compositional techniques, and sometimes they become more serious projects, but usually they're not anything I'm willing to post.
Thanks for your feedback 🙂