In this paper, we address the problem of medium access control in ad-hoc networks with fully adaptive array antennas. We show that, unlike in the case of directional and switched beam antennas, significant performance improvement can be leveraged with just a simple extension to CSMA/CA that we refer to as CSMA/CA (k). We then provide PHY layer based insights into why a MAC scheme that is smarter than CSMA/CA (k), and hence can achieve significantly better performance, is possible in the target environment. Finally, we propose an idealized protocol called SMART-MAC that builds on the insights.