I politely suggest that some of the injury is self-inflicted. Among the multitude of brochures advertising the diverse events open to the public, I have never seen one for the Dulwich Picture Gallery. Consequently I do not know its precise location, nor how to get there by bus or Tube, let alone know anything about the museum or its exhibits.
The National Gallery publications, covering the design and construction of the Sainsbury Wing, give generous praise to the Dulwich Picture Gallery. Surely the opening of the Sainsbury Wing would have been an ideal time for the Dulwich management to capitalise, in every sense of the word, on the free publicity?