There is great vulnerability and humility exercised in this Scripture. Not on Jesus' part but on the part of the disciples. Imagine, having your friend, your teacher, your Savior bend down and wash your feet. This task of course was usually left to the servants of the house. Not much to mind about that, there is not much of a relationship built between servants and guests. There is also the aspect that in Jesus' day there was no underground plumbing, animals walked the streets and defecated on the paths people would walk, garbage was thrown into the streets....you get the picture. And Jesus insists on washing my feet, I don't think so.
But here is the point. How can Jesus do ministry for people who are unwilling to take off there shoes? This isn't about our own defenses being exposed but rather it is about the share in what Jesus does command. "See, I am giving you an example so that you will have to do as I have done to you." (John 13:15) There is a great humility knowing that Jesus is willing to wash your feet. There is also a great vulnerability to allow Jesus to see all of the stuff that you been carrying from the road that you've been walking. There is a great deal of trust having Jesus see what I have been carrying on my journey and yet Jesus doesn't care....he simply wants to wash my feet. There will come a time when you will get the chance to have your feet washed. It will expose some things you may not like, holes in your socks, lint between your toes, stuff you have carried throughout your journey. Taking off our shoes is allowing God to intervene and wash what needs cleaned.....and this is true even if you don't like feet.