"Like it always has" is a little misleading, because the mechanics of turning vs. hit dice used to be very straightforward. I'd rather it be closer to the way they did it in 1E / 2E -- that is, each undead has a "class" it belongs to. A Wight would be "Class VI" or "Class 6"; if it's Brom Bones, the "Headless Infernal Champion of Orcus" Wight, then it's "Class VII/Class 7" instead. Roll a die, compare it to a chart based off of a simple math comparison formula, and you have your answer in 5 seconds.
I really dislike turning it into spells, and would rather have it a choosable talent instead. As a spell, that means it's unprepared sometimes, and for the clerics who can do it, I'd rather they can do it all the time, instead of having to prep for it, even as an encounter resource.