Checking with Will Thompson and moving status to backlog
155 votesMichiel Rozema commented
Something like this is definitely needed for larger and more complex models. Specifically the first use case as Daniel states below.
The idea of a global variable is not tied to table variables only, although scalar variables can be implemented through measures today. The fundamental difference with a calculated table, obviously, is that a global variable is evaluated at reporting time in a context-dependent way.