That's one of the "strategic implications and future directions" in the Advanced Advertising Media Project summary report on "Remaking Video-on-Demand to Deliver Media Value". It's almost hard to remember that VOD launched with great promise -- everyone wants the opportunity to watch things at their convenience. Then the business realities/choices/jockeying came out: Comcast took the position that it would not pay extra for programming for its VOD platform, the advertising had to be locked in at the time the program was delivered and Nielsen wasn't set up to measure the viewing. Given this combination the programmers treated it as a platform for marketing -- clips, a place for sampling of new shows and the like. What might have been a premium platform became a promotional one and a divided one since every distributor had a different strategy for VOD depending on their technology (DBS) or the economics of their footprint (CableOne) or their belief in charging extra for SVOD (Cablevision). Also, nobody had a good way to navigate the choices (no iPod scroll wheel or recommendation engine innovation). The victors of VOD -- YouTube, Netflix and DVRs -- all had the benefit of not having a seat at the table.
Advanced Advertising Media Project (download page)