Jacopo and Nicola are indeed the gentlemen of Verona because instead of earning a living through immoral practices, they decided to earn their daily bread by standing on their own feet. Both of them are selfless and shows selflessness and reflects great dignity in their behaviour. They were deeply devoted to save their sister from the clutches of her illness. In their earnest endeavour, they became role models and epitomes of sacrifice who can enlighten the path for rest of the humanity to follow.
Hence its no wonder when we call them the two gentlemen of Verona.