in case anyone's still interested, i found this rationale for wayland on jolla on WIKIPEDIA.

Carsten Munk, Jolla's Chief Research Engineer and one of key persons in Mer project, has made it possible to run Wayland (display server protocol) atop Android GPU drivers. It's being done with glibc rather than Android's Bionic libc derivative. The solution is to enable the use of Wayland on top of Android hardware, particularly with its GPU drivers. However, as part of it, for the operating system to not depend upon Google's Bionic libc library. In April 2013 the code is at a stage of being able to handle a QML compositor on top of Wayland while rendering to Qualcomm's GPU Android drivers. The motive for engaging this work is that most device manufacturers are only willing to work with Google's Android and not supply drivers for X11 or Wayland or other platforms.