When's the last time your put yourself in your customers' shoes? Not just their shoes, their skin?
When is the last time you had a long hard day of work and tried to use your own product like someone who expects things to be easy after a though one?
When is the last time you got really angry because something didn't work right when you finally had time to play with it?
The clarity such empathy can offer you is tremendous. You can find easy fixes, simple rewrites that will have a much more massive impact than some of the ambitious engineering and design projects you have underway.
All it takes is to stop building for a moment and experience the other side, and you just have to do that once in a while.