We've all heard this before.
I use it a lot when I need to accept things I can't personally change.
When it comes to me, I try NOT to use it.
After all, just because something is the way it is doesn't mean that it can/will/should stay that way forever. Especially when it comes to behaviours or attitudes that could use adjusting.
I think a lot of people have an "it is what it is" attitude about their websites and online presence. If they looked carefully, they'd find things that could be improved. No improvement takes place though, because "it is what it is" - it's "good enough" for now.
I remember hearing someone say that "good enough" is a synonym for "I have no reason to do better".
Do you have a reason to do better? Then "It is what it is" probably isn't good enough for you.