The lambda calculus with types equals to intuitionistic logic. (from the Curry-Howard Isomorphism)
Intuitionistic logic is asymmetric and is constructive.
If we want the logic to be symmetric and constructive we should restrict the copy of assumption from the linear logic.
So we can introduce the symmetry to the calculus by the copy of variable.
I think that a symmetric structure is more beautiful than asymmetric one and symmetric one is more maintenanceable.
So I think that it is good that we restrict the copy of variable or wrap that by a library. Is it right?