The risk with removing the ATPL flight test is that we end up with a licence that some if not most ICAO states will refuse to convert. This would impact on those seeking employment overseas.
It is even conceivable that ICAO would not recgnise it as a licence. The days of printing tickets out of a vending machine just because some magic number of hours click over in the logbook are long gone.
The better solution would be to allow the test to be conducted in less complex aircraft. Maybe not an Islander, but certainly there are light twin turboprops that are suitable. If the test is allowed to be combined with an IPC it becomes affordable in that no pilot seeking or maintaining employment at ATPL level will not have to renew his/her instrument rating.
Another way to look at it would be to have the ATPL test in isolation similar to the USA but have the IR issue combined with it then the IR perpetually current subject only to recency in approaches and instrument time. The FAA allows this and, as others have pointed out, their safety statistics are better than ours.