"Some of the songs in this book... cannot be sung" — Charles Ives, "Postface to 114 Songs".
Not writing enough (i.e. almost no) songs. Why? A terrific fear of words (sounds, meanings of words, appropriate scansion, emphasis) and not being, myself, a singer. The last, in part, due to the highly gendered ideas about singing (i.e. boys don't, except rock stars) with which I grew up. But still no excuse.
The still-precocious Mr. Muhly has a useful handle on songs (here, amid sensational footage), focusing rightly on their plasticity & transportability (qualities common with currency — are songs the currency of dreamers?), their ability to survive intact in alternative arrangements. (All Along the Watchtower, anyone?) But still, the term "setting" is unnerving, as if one is taking words and putting them someplace so that they don't run away. You see, I want words, like sounds, to run away, to go to all the places they can take us, and fixing them to tunes can often tie them down to one meaning rather than another, making an uneasy balance of gains and losses. Perhaps that's why the best songs are seldom settings of the best poems: the loss of textual ambiguity is made up for in the added value of the music, which might even add ambiguity of its own (are there better examples than Schumann's In Wunderschönen Monat Mai and Ives's The River?).
Maybe the key is avoiding falling in love with a text. The more I read of the Georgics, for example, Virgil's incredible didactic poem about fields and groves and cattle and wine and honeybees and nymphs and gods and Orpheus and everything and everyone else, the greater my trepidation of committing to one aspect and not others and of tearing into the poem with the brutality necessary to make a song. I don't know a piece of music which contains as much of this world as this poem does, and I don't know that a piece of music can even have that ambition. And as much as I want to share my enthusiasm for these words, and am willing to be musically ambitous about it, the injury of the necessary excerpt is increasingly hard to accept. Composers: love words, but not too much!