First of all, I like to call this not a plan rather a birth wish, Birth Wishes, usually there are more than one for sure.
I give my clients a very large birth wish list and I go over it item by item and than I ask that this activity mom and partner do together, it gives them a chance to discuss the many options there are and to even do a search to question anything on the list and whether what they select is actually what want for themselves and their baby.I am very explicit in letting them know, that should there be anything they are not at all flexible on, to please let me know, so that I can help with it being respected.
Many clients often say after the birth, that the birth wishes were not followed at all and so much for all that work. I know sometimes, things get out of hand and out of focus during a birth and especially a hospital birth, but at least, the wishes are outlined and many times, Doctors and Nurses will go over it the birth wishes diligently and explain any and all things they feel they cannot guarantee for protocol reasons.
At the same time, it helps all of us know, Mom, Partner, Doula, what we are hoping for and where we to need address certain things should they arise during labour and birth and after the birth as well, wishes for the baby are very important too.
So whether or not, you feel birth wishes are necessary, I find it is always nice to have them nearby, so that everyone in the birthing room is aware of the expectations of the birth.