It's not even about whether ti's overpowered or not. They can change the numbers on this one or on the old one and my opinion is unchanged. It is engaging gameplay. The initial gimmick will wear out in a few weeks.
The new design just removes all skill from using the rune. No more hunting for soul pickups in fights or expertly using camp/cannon timings to sync with ganks our double applications on invades, no more managing power curves intelligently (till 150) and testing pathing (not the best way to get souls but still important) etc. It also doesn't work as a split push tool anymore since it no longer applies on structures.
It's just an empty damage option with no compelling gameplay besides "wow, I do more damage". It doesn't really change anything meaningful in decision making. If someone was near 50%, you'd have targetted them anyway regardless and if a fight is bad, you still won't int just to get a soul stack (at least if you're trying to win). The old DH, when used to its full potential, had meaningful gameplay alterations in everything from pathing to positioning and to playing around the stack timer, 150 power spike etc. It was by far the most interesting rune in the game to me. Now it's just a super dumbed down snowball rune.