The one that came on my New Holland 820 TL is very similar but the movable rod is not completely hidden by the jacket pipe. There is a yellow target piece that slides up and down on the shaft to set the level by referencing it to one of the mounting clips. This is very practical because it is universal with different buckets and you can set it to another point if you just want to dig in a little.
As you said, doing it by feel becomes the norm anyway after a little practice, so it is just a gimmick for new tractor folks.
Here is picture of what I described above. Works fine on level ground where the tractor wheels are on the same plane, but how often is that...