So, I read through it, and I can only abide by the conclusion and thought process.
However I would argue against scaling osmoregulation with total hex count (linearly or not). As you actually highlighted it, the problem should not be merely deciding to place parts or not: a key, little-used mechanics is where you place parts. The denser the cell, the smaller osmoregulation costs should be. Of course, the real challenge here is to find the right formalisation of this latter sentence.
In addition, I would just point out 2 minor disagreements I have with some points.
- I think you underestimate plant gameplay a bit. In fact, you also have to defend yourself from predators (gain speed and/or defensive abilities (pili, toxins)). It doesn’t invalidate you points, but it makes for alternative problems which we can leverage. Note that, in the case of pili, it is of the utmost importance to decide where to place them.
- Isn’t greater surface supposed to incur higher osmoregulation costs? Since you have more points where energy flows away.
And finally, a link to a previous earlier comment of mine, which relates to the topic (dwarfism & gigantism) and you may, I hope, find of interest : Game Design Discussion - #3 by Maxonovien