I de-barb all my treble hook lures or replace them with single hook barbless. I have not noticed a dropoff in landing percentage and in fact if anything, I am more careful on the way in.
"why" - that has been answered adequately. If your not going to keep it (I kept one last year and will not keep any this year) why hurt it? Triple hooks are damn near impossible to get out of a fish, especially at the canal or places like it.
Has anyone experimented with alternatives to lead sinkers? I hear they are knocking off the wildlife because of poisining?