At present, the only dropdown menu for the simple "Membership" filter is the option "is". This means we can only use this to include people of a certain membership category, not exclude them. That makes it very difficult to create a dynamic filter suppressing certain membership types without the use of tags. If the option "is not" was added to the dropdown it would solve this issue (let's face it, given the dropdown only has one option it's currently redundant, so let's make it useful!).