Would you like the corruption system more if the corruption dropped as tokens/enchants? So you could choose yourself which item you applied it to (still not trinkets or Azerite gear).
The corruption of the token/enchant (and rank) would still be based on RNG, but at least you would be in control of which item that corruption should be attached to. This would remove one layer of the RNG. You could make sure that a 12% Crit-increase (corruption) wouldn't be attached to a Mastery/Versa Ring or that those rare Gushing Wounds corruptions would be attached to 475 items instead of 445.
For me personally it would make the acquisition of the corruption a lot smoother and less based on RNG. Because it plays a huge role which item the corruption is attached to. There would of course still be other issues with the corruption system but at least would problem would be (partly) fixed. In my opinion.
Edit: Another idea would be to allow you to buy a corruption-token with corrupted mementos from Wrathion similar to the socket-token you can buy. The corruption-token would then apply a random corruption effect to an item of your choice. Maybe specific corruptions could also be bought (with corrupted mementos) but be very expensive.