It is the BIG number in the instrument scan - much easier to see, while trying to maintain control of an aircraft, than a GS or wind indicator over in the corner of a flight display. It is THE number drilled into pilots as the critical thing to watch
Fair comment, but I guess it depends on the type of display. In its discussion on erroneous airspeed, the B737 FCTM under Non-Normal Operations section, discusses flight instrument displays and airspeed unreliable. Among other things, unreliable airspeed indications can result from blocking or freezing of the pitot/static system.
If the opportunity arises ask the simulator instructor to set up a blocked captain's static vent on take off. Shortly after lift off, not only will his altimeter not show a positive rate of climb but the airspeed indicator reverses and slowly goes backwards triggering windshear warnings and eventually a stick shaker. It can be thoroughly confusing to the unprepared which is why it is such a valuable training exercise in the simulator.
As the FCTM states, if the crew are aware of the problem, flight without benefit of valid airspeed information can be safely conducted and should present little difficulty. In addition, ground speed information is available on the instrument displays assuming you know where to look for it. If you don't know where to look for it instantly, you should not be in the job.
For all the reasons given in the FCTM, it is a good idea before starting the take off roll to know the headwind or tailwind component. Not only is it a good idea but a vital aspect of good airmanship. Thus, if a 20 knot headwind is present on take off, it takes only a fraction of a second to glance at the ground speed reading at the 80 knot or 100 knot airspeed call and know that the ground speed should be roughly 20 knot less than the airspeed.
Now, if a significant airspeed discrepancy is noticed between the PF and PNF ASI readings at the 80 knot or 100 knot call, and there is momentary uncertainty which one is correct, a glance at the ground speed indication will offer a clue. if necessary, the pilot can fall back on the ground speed display to take whatever action is appropriate. Normally it is safer to keep going rather than risk a high speed abort.