The PP dates from 1929 and the PPK from 1931. As such they were innovative designs incorporating the first practical DA, de-cocker equipped operating system on a pistol.

The heavy DA trigger pull is an artifact of the geometry and the resulting leverage available and their isn't anything that can be done to reduce it.

However, it's not unmanageable by any means, and in fact I owe a lot to the PP series pistols as once a shooter develops the grip and trigger finger to manage its 12 pound or so DA trigger, your DA shooting will be awesome on any revolver with a lighter trigger.

In the extreme, if you want to develop a new perspective on triggers, get an 1895 Nagant. It has what is without doubt the heaviest, grittiest, hardest to control DA trigger ever produced. Once you master it, everything else is a walk in the park.