The phrase 'remain outside controlled airspace' has always been an option for ATCO's to use, however, it recently became mandatory if the ATCO cannot give a joining clearance etc to the pilot without delay. Now, i have to apologise here, i can't remember which MATS update/ATSIN etc etc it was in so i stand to be corrected.However, i'm fairly sure that's why the phrase is more 'prominent' now on the r/t.
There were conversations along the lines of dumbing down, pilots should know not to enter CAS without a clearance etc between ATCO's when and since it was introduced.
We seem to be stuck in a vicious circle of lowering standards; airspace infringements are rising, caa introduce a new phrase telling pilots what they should already bl*** know, phrase gets overused and becomes just another pointless procedure designed to protect against some sort of litigation. I can see it coming.... 'sorry your honour but the controller never said 'remain clear...' so i thought i could transit through ....
O.K. i may be pushing it a bit, but my experience matches that of STANDARD NOISE's The only feedback that CAA ever gives is 'no action taken, incident closed' following an MOR for infringement.