No, I think it's quite clear how it works. You are fine with a cloak, but otherwise you are in danger. Period. It's pretty straightforward. The only DM interpretation is whether the DM should acknowledge the weakness at all. But, should we extend that to the other weaknesses the vampire has? Should I not use Radiant attacks against the vampire? Oh! That's not "fair" because that's taking advantage of a specific weakness the vampire has! Or, maybe we should drop that whole "being undead" thing too... That's not fair either!
Really, this seems to be only an issue for people have problems with characters having "weaknesses" that aren't "fair".
And, to that I say: don't play an undead monster of the night.