Liners are decoratic when used with synthetics such as micarta and G10.
But they serve a function when used with natural materials. They provide a small buffer between the natural material and the steel of the knife. Natural materials expand/contract with changes in humidity and temperature. Steel doesn't (not at the temps I'm talking about). So the liner stays put against the steel and allows some flexibility for the natural material to "move".
:thumbup:
It's all a game of compromises. With the extra weight you get durability and strength.