My understanding is for both legal and practical reasons.
On the legal side, at the Fed/constitutional/4th amendment level our agency attorneys and the FLETC legal training program agree that display of a weapon including pointing/muzzling with a firearm by an LEO is a display of authority, not a use of force, though as noted above it still requires specific RAS. Documentation as part of the arrest or incident report is recommended as best practice but a use of force report is not required since U de federal law it is not a UOF. State law and your agency policy may differ.
From a practical perspective, low ready has some benefits, a huge one being it gives you a better view of your suspect or the area you're searching. However, we've been teaching the press out from the holster for many years. They would refer to it as prepping the trigger and pushing the sights but it is the press out under another name. We found it took more time to come up from below ready then to press out from the compressed hi ready. Both the reaction time and accuracy were better coming from the compressed high ready than from the low ready. You could say our results are biased since our guys start all but one of their qualification Stages from the holster and then pressing out or you could say we're taking advantage of commonality of training.
One of the negatives of the low ready his officers think of it as a "safe "position when in fact they're often muzzling the legs and feet of officers, suspects, or third parties in close proximity. Currently we are teaching the compressed high ready and have them go to a Sul /NRA safety circle position to avoid muzzling people who don't need to be muzzled. They can press out to high ready or aimed in from either of these positions if necessary. It's not a perfect solution, since you can wind up muzzling your own feet when moving in Sul.
One negative to dropping the low ready has been trying to ensure all of our officers understand the difference between the high ready and aimed in and how aimed in blocks your view and hinders you when you are trying to search and/or assess a suspect.