They aren't on all charts. There are criteria for when they are charted. I just don't remember what those criteria are. That said, you can still compute your own unofficial VDP on any straight-in approach to help your situational awareness and predetermined choices on what you might want to do depending on how far out you are when you see (or don't see) the runway environment. All you need do is figure out how much distance it will take you to descend from MDA to the runway -- which is a function of HAT and the descent angle you normally fly visually.