No.
1) My philosophy is to keep weight low. Yeah, compared to the rest of any vehicle the jack isn't that much weight, but it all adds up. Also, more weight up high mounted on things (like a rack) tends to put weight and force on those parts that they don't need - maybe weren't made to deal with. Remember, when you are moving over rough terrain how much the top end of any vehicle moves about, side to side - when you add weight to motion you get force, and it can do bad things.
2) What if it falls off/breaks off/etc.? It is going to do more damage from high up than low down.
3) When you need it, do you need it up high like that? Or do you need it down low? I think 99.9% of the time you will need it below waist height. Why go to the extra work of lifting it up there and then taking it down when there are handier places to put it?
Personally, the only things I am going to put above or on the roof of any of my vehicles is going to be lights, maybe horns, solar panels and a few other lightweight things. Maybe an exo-cage will go over the roof. But only things that are lightweight and benefit from being up high. As it is my expo rig will already be high - I don't need to make it higher.