I customised my B17 as it didn't really work well with bars below saddle level - too much chafing on the side flaps.
It's now a poor man's Swallow, replete with a riveted underside plate to prevent sagging. Well, the underside plate is actually the side plates from a link of old chain, but it accomplishes the same job.
Why? Many riding saddles (horse) have amazing designs on them which get just as much use as a bike saddle - as long as you use saddle soap and keep up the maintenance the customization will last for decades.
In regards to the looks, many riders customize their rides whether it be matching cables and hoods or paint schemes - bicycles are very personal things, we bond with them and making them that little more unique.