The other way around can also work quite nicely-Pictures At An Exhibition was a piano piece and the orchestral versions are among audience favorites.

I think when you are doing transcription, only thing you can't forget is the original :-). Liszt's transcripitons are maybe good if you are pianist and have irresistible longing to play "symphony". But it is interesting for me as a listener? Not. Transcriptions of works made by other composers are works of "lower category".

Yes, this is one of the exceptions. In this case instrumentation gave new dimension to the work. Also, sometimes are transcripiton very useful, especially for students and amateur players (piano reductions of orchestral parts in concertos).

But I just think that transcriptions are in 95 % less interesting than originals and audience knows it. For example Schoenberg's orchestration of Brahm's Piano Quartet in g minor. It exists, but how often can you hear it in the concert hall?

Do you like Tartini's "Devils Trill" sonata for violin and piano?
Well, nearly nobody plays the solo violin original. Everybody plays
Kreisler's arrangement. And what about Mussorsky's symphonic
works?. Listening to them, you are really hearing Rimsky-Korsakoff.
And if you are fan of Chopin's nocturnes, it's a sin listening to the
Sarasate,Milstein or Ricci transcriptions for violin and piano.

Good example...Rimsky-Korsakoff' changes in Mussorgsky's partitures scholars consider to be negative feature today. I and very good understand why. For example Slovak National Theater has Mussorgsky's original long version of Boris Godunov on the repertoir. I wouldn't go to the performance of Rimsky-Korsakoff version. That is just my opinion, I said all to the topic of transcriptions.