The MCPE counterpart of MC-107749 , which was marked as WAI. (And then reverted to not WAI, and then later made WAI again due to community feedback. It remains the intended behavior as of 16w44a.) MCPE observers, in order to be consistent with the Java edition, should strongly power blocks, instead of only activating the blocks immediately in front of them. See attached picture for comparison.

Interestingly, observers already act as if they powered pistons through blocks because of MCPE-16286 . So changing MCPE observers actually wouldn't break most flying machines. The community also seems to be in favor of changing observers as well, so I don't think there would be any backlash against a change to strong power.