My own thoughts are that it depends on each individual father.
It is important to respect and protect his participation in the birth of his child.
My own DH, who did feel it was a personal experience between he and I, appreciated those who interfered as little as possible with our experiences.
I would have liked a doula, but at that time, there were none, at least not in my area. My DH says he would not have minded a doula, if she was a doula who has a quiet presence, and instinctive. I know in the short and arduous birth of our third son, he was grateful for the two L & D nurses who acted as doulas, and essentially "held the space", and kept the door shut while I walked around, stood, squatted, etc, never once offering anything in the way of "medical" assistance, no monitor, no drugs of any kind, not even a hep lock. They taped my birth plan to the door and made sure it was followed.
I don't think we are asking too much from fathers in birth, we just need to remember that like us, men are all different, we should not generalize, we should try to be a "quiet presence" and individualize our care to meet the needs of the mama and her partner.
At least that is what I believe...
P.S. His participation did not hinder the process, I wanted him there and he wanted to be there.
Did not change our sex life at all, I think he wanted more. :LOL
He is pretty good at keeping any "reactions" to himself. The birth process does not scare him.