Could landing gear weighing scales be used to detect lack of lift?
Technically one could develop a system that compares the decrease in weight-on-wheels during the take-off run to a theoretical lift model in order to determine whether the wings are performing as expected. 

I see a number of reasons why this will not be successful a product:


Limited benefits:
The benefit of such a system is minimal. There are very few crashes due to contaminated wings or wrong flap/slat configurations. Let's assume there are one hundred thousand airline flights per day and one lift related take-off crash every 4 years. That is one in 150 million.
Available alternatives. 
For both causes there are viable alternatives to detect them well before V1. Visual inspection of the wing usually detects contamination and many aircraft automatically check for the take-off configuration to be set whenever the thrust increases beyond a pre-defined trigger level.
Increase in number of rejected take-offs: No system is perfect. It will detect some contaminated wing situations and save the day, but it will also cry wolf in cases where there is nothing to abort a take-off for. If the system has a false alert rate of one in ten thousand take-offs (which would be very good and expensive to design and certify) it would cause 15000 aborted take-offs (assuming the same numbers as above) for every crash it prevents (assuming a missed alert rate of 0).


Since lift increases with the square of air speed, it is difficult to detect lack of lift early on during the take-off run. At low speed there is relatively little lift to be expected and it will be in the noise of the measurement. Also the accuracy of the airspeed indicator is relatively low at low speeds, so the theoretical lift model will not give accurate results either. As a consequence the system will only be able to detect lack of lift at high speeds. At those higher speeds, the influence of bumps in the runway start to affect the measurements as well. It is easy to see that detecting lack of lift is no so straight forward. False alerts will be raised and they will be at raised at high speeds. 

High speed rejected take-offs are risky. 


  Boeing studies indicate that approximately 75 percent of RTOs are
  initiated at speeds less than 80 kt and rarely result in an accident.
  About 2 percent occur at speeds in excess of 120 kt. The overruns and
  incidents that occur invariably stem from these high-speed events.


So effectively such a system will likely increase the number of accidents.