There appears to be an increasing tendency for crews to rely on reverse thrust to stop the aircraft. Certificated landing performance should ensure a safe landing within the assessed ‘factored’ conditions, thus the priority should be to get the aircraft on the ground (right place and speed), deploy spoilers and start braking, and then follow up with reverse.
Reverse thrust in many aircraft may have the lowest probability of working reliably; hence it is not used in certificated landing performance (exceptions apply with risk mitigation, e.g. contaminated runways).