"Lord of Death"???
This title change is even worse than the "Mistress of the Blade" idea that they almost passed off on Fiora. "Lord of Death" takes away Morde's personality, of which he didn't have much to begin with.
The idea of a hulking suit of armour whose vengeful spirit rocks out to heavy metal is pretty awesome. They took a Sauron-esque figure and spiced him up with a musical theme, which happens to align with what he actually is perfectly. This is a HUGE step up from a horrifically generic "Lord of Death." You may as well take this joke full circle; make the title xXxLordofDeathxXx or 666LordofDeath666. Or maybe you could come up with a title that doesn't sound like an 11 year old's CoD tag.
I think that when Riot goes deeper into his rework they will treat Morde's musical affinity as if it were old Sion's Arnold voice. Back when Morde was designed there wasn't a super serious framework for lore. Morde could be a huge metal fan because it was cool, and that was good enough. But now, maybe that doesn't fit in to the "healthy home" that they feel his lore needs.
RIP