A BSP is only for the easy of hobby-imagebuilders; using a BSP they have no work to do at all to support hardware, and they can blame the manufacturer for everything that is not working 100%.
Quite correct. The manufacturer chose to build a closed-source infrastructure and must therefore bear the consequences. The BSP clearly marks the boundaries between what manufacturers are responsible for, and what the team will do.
If any manufacturer provides open source drivers and hardware, my offer of creating and maintaining Linux support (in other words: The BSP) for free still stands.