Overuse of local variables is probably worse than the "mess" created by long wires. It increases memory usage, violates data flow, and increases probability of race conditions. A better solution to long wires is to make the diagram smaller by using subVIs. There's been a lot of discussion here and in the various LabVIEW style guides about avoiding local and global variables. I use them seldom and only then when I doing some complicated user interface.