You have always been able to use the MOI interface:
julia> model = Model();
julia> MOI.get(model, MOI.Name())
""
julia> MOI.set(model, MOI.Name(), "My Model")
julia> MOI.get(model, MOI.Name())
"My Model"
I’ve opened a PR in JuMP to add support for set_name(::Model, ::String). We already had name(::Model).