It occurred to me that some of it might seem obvious, perhaps even inconsequential.
"Of course I live in a world that is constituted primarily by language. Of course I do what I do because society tacitly decides upon these things. So what? Why does it matter if the social world is constructed out of linguistic categories? Why does it matter if my experience is constituted primarily by a symbolic order? What's the big deal? What difference can it make in my actual life?"
I think that it is important to recognize the existence of symbolic order because it enables a greater degree of freedom. If social existence were constituted primarily human nature, for example, we would be in a deterministic position. Social order would be set by things beyond our control.
And this is the main thing that this notion of symbolic order needs to overcome. This idea that human experience, social reality, and even human nature itself, is constituted primarily by language needs to overcome the idea that humans are biologically determined or set.
Because if we continually appeal to evolutionary biology, bio-chemical determinism, or the like, we do not have a philosophical underpinning that supports positive social action.
But if we accept that human nature and social reality are constituted primarily by language we have a framework that allows us to make genuine choices. We can choose what rules we want to conform to. We give ourselves the opportunity to create ourselves.
Unless we accept this view of human nature and society we are left with a lot of shoulds and oughts. And while this view also comes along shoulds, it offers a lot more room for creative self-creation, both individually and socially.
In short, viewing human nature as constituted by language provides a philosophical framework that supports and encourages self-creation. While accepting that human nature is largely biological leaves us wondering how we are to go about the business of social progress, how to go about the self-conscious creation of our historical life.