Why do pianists...

[bamba]

...always get their nose so close to the keys when playing softly?
I've begun doing it also and I can't really tell why...

[richard black]

Always? Not in my experience. I don't, for a start, and my wife doesn't either.

It's a small point, but I always discourage pianists from moving around too much while playing because it distorts your relationship to the instrument and makes you think you are producing varied dynamics when, in fact, you're not (and vice versa).

[liszt1022]

I end up showing 0% expression in my face while playing, I try to make sure it all comes out through the notes.

However, for some reason I can't help but get my nose close to the very end of Moonlight Sonata! Right at the Fx-G# octaves before the final bars. I've never done it before, and it just came up last month...

[pianoviolin]

why do pianists... move their mouth while playing?

Most of pianists I've watched perform move their mouth through some passages, and it's contagious i think because I've been starting to do it.
It's quite weird. I have no idea why I do it. are they trying to say something or what?

[bringdowntherain]

From those I know - and doing it myself - they do it because they are just getting into the feel of music. Bringing yourself closer to the piano compacts your body and compacts your movements giving you a feel of the softness of the piece.  It is required?  Not in the least bit, and not everyone does it.  Is it good form?  Probably not, but I do find it useful? Yep.

[bachbrahmsschubert]

why do pianists... move their mouth while playing?

Most of pianists I've watched perform move their mouth through some passages, and it's contagious i think because I've been starting to do it.
It's quite weird. I have no idea why I do it. are they trying to say something or what?

We are singing! It's a habit of mine. I don't sing audibly a la Glenn Gould, but I'm always singing in my head, and sometimes my mouth will move without trying.