I can't tell you by now just how many times we've discussed this topic. In fact, just yesterday it came up again. We see a need for a person-to-person direct messaging in all kinds of scenarios. In the future (unlike now) most people using Cake will only know and meet each other here and have no other channels of communications. Publicly posting your personal contact info is not something most people would want to do. So the solution is the direct messaging.
We want to do it right and make it easy to use, which takes time and priority. Given that we still have Search and Activity Stream to solve, this is going to take a back seat but it is a feature we are planning for in the future and it is something I personally advocate for.