Slasher,
We are not sure why Boeing changed their philosophy, but it appears to be post SR111 and applies to more than just the B737.
The QRH data is giving you test pilot stuff for when you HAVE to land your aircraft immediately, use them at your peril for normal operations. You would be a lot better off sticking with your old graphs that presented a pre-departure “Landing Distance Required”.
Cheers
Mutt.