I fully understand the concern from an ATC point of view, however, it's illegal not to fly at MSA when you're IFR outside the controlled airspace, even if flying under someone's "stub" or TMA.
There are a number of major airports in UK where flying 100 feet below controlled airspace (including almost the entire London TMA, i.e. Class A airspace) is the only practical & legal thing to do when the weather goes below VFR limits, due to the relationship between MSA and the airspace above.
This seems to have been "designed in" by the ATCer's themselves!