Research focused on the power / wing area ratio, rightly or wrongly, rather wrongly in my opinion, since I mention other ratios such as power / space use which would favor the rotary AWES. Crosswind kites have a better power / wing area ratio, but not power / space use ratio, excepted by using low radius loop paths.
I would make an analogy although it is not quite exact: crosswind and rotary kites could correspond respectively to airplanes and helicopters. Airplanes have a better power / wing area ratio, but require a lot more land use for takeoff and landing operations.
In reality, rotary kites, by their constrained flight, maximize the swept area (in addition to facilitate take-off and landing), compensating the relative (and sometimes negligible when the blades are far apart as for Daisy before scaling up) lack of power / wing area ratio.
However the power / weight aloft ratio favors also crosswind kites compared to rotary kites…
Otherwise, this document seems to show a transition towards a theoretical scientific focus by the importance given to work on control (key word for this topic), which could possibly benefit other industrial fields.
To show the progress of AWES in 20 years, it would take at least a chronology of tests showing duration, and power curves.