I have heard many an expectant folk say, "why do I need a birth plan?" "It makes you sound demanding," or my personal favorite, "I don't need one, I'll be fine!" Birth is better with a plan, or at least with clear wishes or preferences. It's not that medical providers don't care about your wishes, but the reality is, when you get admitted to a hospital, you are now a patient and you will be offered medical choices! Your providers won't know your wishes, unless you do. My advice, write it down.
Having a birth plan, encourages you to think about what your options really are, and you do have options. What if I told you that you don't need to have that icky IV port right away, you can have it later if you choose to have pain medication. Or, that often you can have intermittent fetal monitoring rather than continuous monitoring. That in fact, continuous fetal monitoring increases cesarean rates. Also, pushing does not have to be the ever enjoyable counting to ten, three times per contraction. Yes, some people giving birth will want/need some direction, especially if you've had an epidural. But the fetal ejection reflex is pretty powerful, people in coma's have pushed out babies.
Long story short, a birth plan, allows you to explore what is available to you during your labour and birth, discover the risks and benefits and make informed decisions that will enhance your birth experience. You want your birth memories to be of you making decisions, not having them all made for you.