...There's no excuse for forgettingto set TO flaps---NONE
I disagree. You can forget to do it for any number of reasons. If something interrupts your normal flow, and things get rushed after that, it can happen. I can imagine where you reach for the flap lever, then ATC calls with a funny request, then your hand never gets back to the lever.
What is unforgivable IMO is that they continued the takeoff.