Greenhaus Education and Other "Effects"

As a person who believes in the integration of technology in instruction, my thoughts about online learning/schooling are mixed.  I read this article "Online Grade Schools Becoming a Popular Alternative"  by Mark MacLaughlin  about parents having their elementary children enrolled in an online grade school and it just got me wondering about what might be some disadvantages to this approach. While I completely agree that it gives children more choice in what and how they learn, does it impact other important aspects of actual brick and mortar schools?  These other aspects include interacting with peers, learning 'rules' and limits (expectations of the real world), learning respect for differences and how to deal appropriately with those differences (in other students, in teachers, etc.)?  I am a proponent of online learning, don't get me wrong, but I just wonder if a mixed approach is better.  I know from my own personal experience with my doctorate course...