SELinux is a perfect tool in its niche — where that niche is "secure-installation system integrators." It's not a tool for regular people; it's for e.g. defense subcontractors who want to certify their virtual appliance as meeting certain standards demanded by certain customers; where meeting those standards requires them to actually go through their virtual appliance from top to bottom and prove the whole thing secure and sandboxed.

It's not a tool for application developers (who at most can supply SELinux templates to start with); nor is it a tool for sysadmins (who really don't have the time or the incentives to deal with it.) It's a tool to be wielded specifically by people occupying a role that, in most organizations, doesn't exist.