What I like about the VM-centric design you've adopted is that 'apps' are long-running by default. Sandstorm in its current form is not great for hosting internet-facing sites.
But, yeah, for a fully-dynamic web site served to a large number of users, Sandstorm currently isn't well-suited. It'll get there eventually, but given that other platforms (like Portal) already cover this use case pretty well, we wanted to focus on the interesting things we can do with fine-grained containers.