Swords are something relatable, its something you can use in real life for combat. Of course your sexual insecurities makes you look at swords as dicks but it is what it is like you said.
There have been actual santoryu users tho instead of mouth swords they switch blades.
But beyond that Zoro has set motivation, a set goal and Zoro knows meaning behind his goal, we see him training hard towards that goal.
What is Rubber Trash cans motivation? Why does he wanna be freest man in seas? What does that mean? What is his motivation behind PK title?