The same year, the annual List of Banished Words contained the phrase, calling it avoidant, meaningless, pointless, and pervasive. (Since then, it is what it is seems to have fallen from favor somewhat, but it may or may not have been replaced by other commitment-phobic phrases.)
The phrase was not always used in such a mushy way. I was surprised to see it is what it is in Mere Christianity, which was published more than 60 years before the phrase made it onto The List.
C.S. Lewis uses the phrase twice in that book. Both times, he is speaking about the pointlessness of asking if something could have been or should have been some way other than how it is.
Lewis uses it is what it is to mean something solid, rather than something indistinct; to clarify, rather than to obscure; to make a point, rather than to avoid one.
And speaking of points, I have one here... somewhere.
Changing times require changing language. But it's one thing if our tentative speaking style comes out of a sincere consideration of others.
It's something else entirely if we're just protecting ourselves.