Oddly, I think if there is any drama at all around that idea, should it be implemented, it won't be over NPCs being played /wrong/ so much as if the PCs don't pay enough attention to the individual and it becomes just like any other generic NPC (which it will to most PCs that aren't previously associated). A lot of WoD people in particular tend to get tetchy about "oldbies" and "new people" disparity in popularity/attention (or the perception). That can be hard enough to deal with with PCs, I wonder how adding that potential to NPCs too might work out. Or maybe it'd be totally fine.
I think you'd have to probably screen the players whose former PCs you used; if you did that and declined the offers of people kind of known for being a bit on the dramatic side, it might be fun. What I think I am hearing concerns wise is a mild concern that it might be a vector for the attention/story to be pulled from the mortal/PCs to focus on the familiar/beloved Monster (which is only going to be super fun for people in the know, probably). It's a little tweak to focus but it /could/ be significant. Dunno. Maybe it would not be though. I think it's valid and understandable to be raised as a concern though.