Hi Dimi,
This is a fantastic question. I think it's been investigated from different angles, but there is certainly room to improve and update the research.
"Revenue matters less than many institutions think it does. Cost recovery and even, in some cases, net income from commercial licensing activities are important considerations for museums. Although a past study has shown that virtually no museum rights and reproductions operation is a profit center (Tanner and Deegan 2002), and although museums generally acknowledge that their obligation and desire to provide information about the collection in as open a manner as possible trumps revenue concerns, revenue remains a topic of interest to many museums today."
"Recent developments in business models concerning the production and distribution of content on the Internet, coupled with a continued examination by museums of their missions and mandates, has led to an awareness that the making available of museum images is merely a means to a commercial end, and not the end in itself. Indeed, in a recent press release, the Victoria and Albert Museum announced that it would no longer charge fees for academic and scholarly reproduction and distribution of its images, claiming that while it earned approximately $250,000 a year from scholarly licensing programs, the overhead costs associated with licensing fees rendered their profits much less.140 What is not reported, but what is suspected, is that the Victoria and Albert Museum determined that it was smart business to allow its copyright-protected images to be made available for free, thereby increasing their circulation and delivering significant promotional opportunities back to the museum.
This sort of decision-making in academic and educational
institutions has been documented since 2001, when MIT
undertook a similar inventory of its IP, allowing certain types
of its academic content to be made available on the Internet
without charge. While contributing to the public good and furthering
the educational mission and mandate of a collecting
institution is primordial, it is argued here that providing unfettered
access to museum images is actually good business."