Apologies for the slow response on this post. I would love to think of ways to fix this. I think most uses of docker today involve deploying applications that you do want completely sandboxed. And for those, this works rather well. Hopefully this doesn't keep you from trying it. (Indeed, you may have a nice solution to this that escaped me.)
That is certainly a path I considered. However, having to setup either of those is not exactly trivial. And not something I care to do for a user application.
This is an interesting problem, and I would think one that a lot of people are experiencing.
Seems like an area of opportunity to make docker images a lot more flexible.