It may have become fewer these days, but many people still have experiences of eating or relaxing with families beneath a tree, or climbing trees to find their own space to play.
It is just a metaphor, but the desirable place for a family to gather and spend time may be somewhere like beneath a tree, laid-back, with moderate sunshine and comfortable breeze.
To create your own space around the trunk, keeping the distance and each doing one’s own thing, seems to be more contemporary and realistic than a decade-ago concept of a living room where a whole family members spend time together watching TV. To have a space surrounding the trunk means, putting it the other way around, to have something to block the view in the center of a space. Your view may be blocked, but the distance from the center or relationship between positions will be clearer than one-room space with an overall view. That means your own position becomes clearer. The circulatory nature of the space would also enable to amplify the distance within a room without being restricted by dimension lines on the plan.
The space inside a tree is a special one for children. They don’t mind it being small or care about climbing up and down. Those factors are rather necessary to feel it as their own place. Just like such a space found during climbing up a tree, it is nice that each family member has a position connected to the whole without being isolated. As the time passes, those positions can be exchanged to allow more ways of having fun.
What happens when light and wind comes in? Not a direct and strong sunlight but soft, processed light or layers of reflected light to lighten up the space fluffily, which should be comfortable. Small light or soft breeze coming in one place could affect the surroundings, be shared and work on the whole space. You can have a glimpse of a relaxed family through the gap (hole) where light and breeze come through. Family gathering beneath the tree, or spending time above the tree are such primitive models but could certainly be applied to the contemporary life.