As described in the project proposal for the Eclipse Modeling Project, support for industry standards is critical to its success, and to the success of Eclipse in general. The role of the Modeling project in the support of industry standards is to enable their creation and maintenance within the Eclipse community. Furthermore, as standards bodies such as the OMG have a strong modeling focus, the Modeling project needs to facilitate communication and outreach through its PMC and project contributors to foster a good working relationship with external organizations.
MDT is a project inspired by the Eclipse community's need for more end user "tooling" from the Modeling project. We seem to have an abundance of frameworks and low-level technologies for modeling, but not much in the way of what most expect to find. Of course, this is fueled by the fact that "other" free or open source modeling tools exist, making Eclipse a bit of a laggard in this area. Hopefully, now that we have the key components in place (e.g. EMF, GMF, UML2), getting the community focused on providing this won't take much longer.