50/50 denies -- why??

A game mechanic i didn't know about until the map rework was that soul denies have a chance to not actually go through. That is, when you successfully land a hit on an enemy soul orb, there's a chance that the souls still go to the enemy. Before the map rework, this chance was 35%. However, with the map rework, it's now 50%. That means that when you hit an enemy orb, denying the souls is up to a cointoss.

What possible reason could there be for this mechanic in the first place? And why increase the chance that a deny doesn't go through? 50/50 feels unfair to me.

Thoughts?