Yes, basically the requirement has to be included in the aircraft certification standards in order to get things to happen. And for that to happen there usually needs to be evidence of a number of accidents that could have been avoided.
Fundamental changes of method also go through a cost-benefit filter and a "testability" filter.
Given at least a few incidents of unpowered flight, approaches, and landing sequences in heavy jets, it would seem the cost-benefit (with reference to passenger safety, in particular) argument could be made.
As regards testability, however, the questions are harder to answer. The low, slow, zero-power flight envelope is about as dangerous as it gets for flying a large, heavy aircraft. One can do testing at higher altitudes, of course, but realistic "ground effect" and flare phenomena combined might either require some live tests of each type or a major research effort to create a data-set that could be used for simulation of all reasonable types. The potential variables are so many (for a 'general-case' solution) and the cost of error so high, it would take some considerable courage for an airframe manufacturer to add this function set and pronounce it usable. Would be pretty much a lifetime career for some bunch of lawyers to litigate about that forever after.
Even with all the computers, maybe seasoned pilots and 'seat-of pants' flying still
are occasionally the best choice, after all?
.