Standing under flying and shooting monster doesn't hurt you

[Barry]

When you are standing underneath a enemy that is flying and shooting at you won't hurt you, but it still shoot whatever comes out of you,
depending in which direction it shoot. The Cacodemon will not shoot anything at you while you are underneath it, but it will bite you, which
will hurt you, and I think this is right. The Pain Elemental could be an example of the problem, but it doesn't bother anyone, because it
shoots live monsters out of it, that will fight you eventually. The Lost Soul is a definite example of the problem, because standing\crouching
under it will not fly under to you, instead it will fly in the direction it is facing when trying to hurt you. These all came out of Doom 2, but I
first saw this happen in this WAD Zen Dynamics, where you stand\crouch under this flying spidermastermind on level 2, and it only shoots
it's bullets in the direction it is facing, but will also not hurt you. Here is what I am talking about:
This is a flying Spidermastermind (you will see it shooting and your blood falls out): http://i49.tinypic.com/2a6rux4.jpg
When standing under the flying Spidermastermind, it doesn't hurt you: http://i46.tinypic.com/qz0rxl.jpg
The monster will instead shoot in the direction it is facing, but not low enough to hurt you: http://i48.tinypic.com/ngq4us.jpg

This is not a problem to me, I use it to my advantage at least. Now, is this wrong, should you just change it or is it suppose to be this way?
I just hope you all understand what I am saying.

[Gez]

Now, is this wrong, should you just change it or is it suppose to be this way?

If you want it the way it is "supposed to be", turn on "infinitely tall actors" in the compatibility options menu.