Well, I´d call genetically altering a living Tree to literally house people, complete with beds and a small closet quite a success.
In addition to the fluorescent plants lighting the streets at night and the (my guess here)glowing algae to light rooms.
The lore tells us that they´ve tamed the majestic gardens somewhat t their liking and even have "engineered" the yubo to its current state.
The high quality weapons are supposed to live and show this by leaking poison.
(which by the way finally needs some true effect, what´s it good for without?
All HQ weapons do need an effect besides the particles for that matter. Fitting to the particles of course

)
But, true, I´d expect lots more of these signs of success around.
Early concepts showed Yrkanis city with a canopy. Why isn´t that InGame?
I´d love to see it, rather than these "broken off" looking tree stumps standing around.
Ok, one could of course argue that 60 years, since their first seeds were laid, these trees didn´t have enough time to develop a full canopy, but come on?
And a true "wall of plants" around the city, not this silly small fence, that doesn´t even keep the yubos of the streets. How´s it supposed to keep invaders out, much less Kitin?
Anyway, arguing about these kind of backgrounds doesn´t really bring us anywhere.
You might just as well ask why, for example The Elves in LotR were immortal and peaceful, or why the Hobbits liked good food.
Its fiction

It´s not realy supposed to make perfect sense or be absolutely logical and impervious to scrutiny.
Its FUN!
That´s part of playing a game that involves imagination, y´know
CU
Acridiel
P.S.:
I think it all comes down to the following.
Why are the Fyros so hyped about fire? - Because they life in a highly volatile place and its the richest resource at their disposal.
Why are the Trykers so immersed in Water, hydraulics and pneumatics ? - Because the live in a place full of water and its the richest resource at their disposal.
Why are the Zoraï buzzing with interest about electricity? - Because they did find loads of Amber and discovered it can generate energy, the figured out how to use it and its the richest resource at their disposal.
Why are the Matis all coiled up in plants? - They live in forests and and its the richest resource at their disposal.