After decades, why does Old-Age-Makeup still look so terrible?

I thought they did a good job in The Curious Case of Benjamin Button. Brad Pitt looked like a real old man to me. And they did a great job making him look younger, too. I thought I was watching Thelma and Louise during this scene.

One reason is that when it’s an actor we know is younger than the character he’s playing, we know it’s makeup. In these days of CGI and other special film effects, which are so heavily promoted, it’s very difficult for us to suspend disbelief about anything having to do with movies.

Perhaps it is because us old people just naturally look bad and the movie folks are actually fairly accurate in their portrayal.

@rojo
What I mean by ‘terrible’, is that you can tell that it is make-up and not an actual old person.

@Pachy
See, I did not know that actress, and as such there was no clash between what was on screen and any image in my memory.

Because it ks not Photoshop, it is easier handling fat digitally than age.

@ragingloli, I only suggested that as one reason, at least for older movie fans like me.