I'm guessing it's similar to why some folks want a dedicated non-spell psionic class, non-magic Warlord, something new Witch, etc...I don't think it is a bad idea to have mystical warriors with strange powers. 5E is full of such archetypes available to play. I don't understand why folks who want special powers with their sword and board grog don't play one of those instead of demanding that the fighter turns into a demigod.