His power is made perfect in my weakness

(This came about from a conversation with my sister in law about how we are both selective in our openness.  I believe that God created us for community and that transparency is the most effective means of a successful relationship.  For our own reasons, it doesn't come easily to either of us.  If you hesitate to be completely transparent it might be worthwhile to take a closer look at why. Who is benefiting and how much glory is God receiving from your choice?)

Why are we so guarded, and is that the way God wants it or does something need to change?

Examining my own reservations of being vulnerable with other people I began by thinking it was about them - their perception of me.  I think it was Abraham Lincoln who said he would rather remain silent and let everyone wonder if he was a fool than open his mouth and remove all doubt.  I'm paranoid of looking like a fool.  But why am I so paranoid? Because I'm more focused on myself than on His kingdom, it's all about me and how I feel.  When I am not secure in my relationship with Him, I am focused on myself.  Turns out it is not about the people around me, it's really about my relationship with Christ.When I am focused on myself I am obsessed with pleasing other people, receiving approval.  When I lift my eyes up to where they belong, off the criticizing world around me and on to the only one who really matters I become confident in who I am in Christ, not concerned with issues of this world.  When I raise my gaze I am able to see the Truth and all the other stuff around me doesn't matter nearly as much. 
There's a sense of control in maintaining a safe distance from others. Control that I need to let go of.  I like to feel safe, who doesn't.  Allowing myself to be vulnerable is not a safe feeling. Therefor I'm going to avoid that situation and keep anything that might be used against me locked away in a vault where only I (or a select few) can access.  It's safer, easier not to trust people with my fragile heart.  But I feel God saying it's not about trusting other people, I need to just trust Him. It is in that place hidden from sight that God wants to use. In our pain, our weakness and insecurities God wants to be glorified.  Ann Voskamp writes "That which tears open our soul may become the open places to see through the mess of this place to the heart-aching beauty beyond to Him."  I think she was referring to a first-person sort of experience, seeing God through the holes of our own life.  But if I can see God the clearest through those places in my life, then couldn't someone else see Him there too?  And how better to use my life as a living sacrifice than to take the parts of me that are hard to give, that I really want to hold on to, and do what comes unnatural.  To ignore my insecurities  and open myself up is unnatural, but for those very places to be what God uses in my life to bring Him glory is supernatural !