There are several reasons this would have been a good hook for a movie studio.

The guy was handsome. It's not like they would be getting an attractive, marketable actor to play someone that looks like Henry Hill; and secondly, the Nicky Scarfo as surrogate father angle and paralysing influence on the young, altar boy Phil Leonetti; thirdly, you have the internecine squabbling and deceit prevalent in the Philly mob during that decade which led to Phil turning state's evidence.

It's Shakespearean stuff. And it deserved to be told on the big screen.

Hell, you already have four or five points you can easily write a 90 minute movie around. Ambitious Nicky taking the precocious Phil under his wing culminating in making him an accessory to murder; Nicky stabs the sailor in the diner culminating in his banishment to Atlantic City; The events preceding and following Nicky as boss; and finally Phil's betrayal; movie ends with Nick disowning and wishing cancer on Phil and everyone close to him as a montage of Phil in witness protection plays.