To be fair, this procedure is not "new". There is a condition known as "stabilizer runaway" that can occur when there is a failure in the automatic systems that control the stabilizer trim (for the autopilot, etc). This procedure is exactly what you would do in that situation to address this issue.
The problem is the MCAS addition to MAX adds a new failure mode that the pilots weren't expecting, and it occurred during a very busy phase of flight.
The problem is the MCAS addition to MAX adds a new failure mode that the pilots weren't expecting, and it occurred during a very busy phase of flight.