Another possible reason why the LCW might have been dropped on pennies after 1861, is highlighted at page 422 of Peck. At the asterisked point 4, it reads:-
We know this, for example, from reverse D, especially on Freeman 26's.
Although this apparently only applies to the reverse, maybe it was decided that it was just not worth the effort of keeping on with the LCW or L C WYON, because of the signature degredation issues.