I believe it's recognition of the same issue that likely caused Hamlin's heart issue is most prevalent in youth sports. Dozens of kids a year die when struck in that particular way with a baseball, softball, knee, whatever in just the right spot. Kids are obviously smaller and less developed physically and therefore at higher risk. Having the equipment and training available within minutes may save lives, in addition to the random teacher or janitor having a coronary attack.
Look, I don't know if it's a good idea relative to cost or not (there are lots of things to spend money on to save lives or prevent accidents) but I think Hamlin's situation raised awareness of this issue, and therefore dialogue on it is natural.