It will be more difficult to sleep now that I know nobody has answered the question: "Why do both known 16x16 solutions to the Octopuszle feature the same diagonal complex?"
Looking at the four corners of the solutions on mindsports.nl, the pieces are nearly identical, and in particular the diagonals are identical. It makes sense that the two hand-solvers would use this symmetrical configuration. The programmatically found solution has different corners.
Still, that amount of constraint is surprising. It would be a nice surprise if that corner symmetry could be proven to determine the diagonal complex.
This gif has an example of a Superko (which would likely become illegal depending on what ruleset you use): https://towardstengen.files.wordpress.com/2010/03/superkoles...
Different rulesets (Japanese, Chinese, Korean) define and handle Superko differently.
Chess rewards calculation moreso than Go. Games are often won in a few tactical sequences.
On the other hand, in Go structure and shape is more important and more long term strategizing is required as plans involve building structures in many parts of the board.
While there are local tactical fights that are important to read, one most also think more globally.
So, I'm not sure that the property that one game is more organic is really the essential differentiating factor between the two games.