Why are senior reps under appreciated, or not appreciated at all? Interesting question. At one time senior reps assisted with training and hiring. First ride alongs were done by senior reps and the input was valued. My guess is that gradually management wanted more span of control. Training was to be initiated by a specific skill set of those indoctrinated into the training program. First interviews were to be done by management, not senior reps. New hires would be funneled down a specific path without the outside influence of a rep.
Senior reps could perhaps even be viewed as a threat to those in power, or reminiscent of a past now gone. Management often view those who decide to stay on as reps as costly career failures.
Gradually it seems that value has turned into a kind of animosity. You often hear that senior reps feel entitled, or do not want to change and are unmoldable. They like their customers too much and don't "push them." Or, they are simply waiting to get out. Given the current level of appreciation I would say that the last statement is most true.
In today's environment of frequent territory changes, metrics, messaging, asset costs, and forced rank, the measurements used to give value to reps is quite different than that used years ago.
So far as AZ's value of it's people:
"They that sow the wind, shall reap the whirlwind"
... and you need look no further than the current state of affairs.