It may sound absurd, but based on the people I know and the over protectiveness of their parents (which is not a dig, I am over protective about certain things as well) I do think that learning to sleep away from your family is an important part of developing independence.
I had a great childhood, great parents, easy going life style. My mum was pretty over protective (but not extreme...she had extremely over protective parents and wasn't allowed to do anything and I know my mum tried very hard to not let it stop us from preventing things) but when I talk to people I have met in my life and heard everything they experienced because they went out in the world and really experienced it, I know that overall my life has been really boring (I'm content in my life, but I can't help but feel a bit envious I don't have these cool stories to share)....when they talk about their childhood it was vastly different to mine....far more freedom to do things at much younger ages. I can't help but wonder if my sheltered childhood did hold me back in the 'spreading of my wings.' I haven't mentioned this to my parents at all, because my childhood really was great, but my mum apologizes for not 'allowing' us to do more and encouraging us to spread our wings further, so I believe that she is aware that she possibly held us back.
The world is a scary place, there's no doubt about it, and when my kids were babies I used to tell people (jokingly) that they'd be flowers in the attic (wthout the abuse and incest) and would live with me forever! But I am watching my oldest push so much for her independence and I have to let go and do things I'm not super comfortable with so she can pave her own way in the world.