Let us try to analyze the arguments going from the particular to the general, from Makani’s own technique to the problems posed by the implementation of crosswind AWES.
Surely Makani knows better what did not work according to their nominal expectation. But the commitments to actors and investors may not encourage full communication of these reasons for a long time. One has only some signs: the lack of power curve, the last crash.
Now concerning more general issues, let us credit Dave Santos to pose the problem of weight in flight for a long time, invoking a power-to-weight ratio. To be clear I think the Power to space use ratio can be still more important. To resume a heavy rigid wing flying crosswind brings together all the possible ingredients of insecurity (of which possible severe crash with wings weighing tons and flying fast and pulling the tether…) and use of huge space, including a very long, very tight rope moving quickly and preventing any secondary use: in return, production should be several MW / unit. The scenarios of farms with closely spaced kites do not take into account changes in wind direction and are therefore not very credible.
So those who believe that better software or local technical and aerodynamic improvements will be able to solve the problems will have to wait a long time. It is a problem of design.