MorpheusML: Make Global element optional?

MorpheusML currently has 4 required main elements: Description, Space, Time, Global

However, it is not clear why Global must be required:

• Global does not have any required sub-elements.
• Perfectly valid models can be constructed with Global being completely empty.

I understand that, internally, the Global scope must always exist. But this does not necessarily mean the XML element Global should be required, should it? I do not see problems to make it optional.

(In writing the manuscript, I had problems defending its required status. Independently, Lutz also commented on this.)