Are there any kinds of nerds that are more intense than video game nerds? Oh, right: theater nerds. So what happens when you put the two of them together? You get a dude dressed Altaïr belting out some dulcet tones about how he needs to take a "leap of faith," obviously.
Assassin's Creed: The Musical comes from YouTubers Inside Gaming and Machinima Prime, the (slightly) more dressed up part of the popular gaming-themed video entity. It's more just silly fun than any sort of serious deep cut for Assassin's Creed fans. But at least they can recognize that nobody—nobody—likes playing as Desmond.
Also the Ezio song is perfectly silly. Why does he sound like he's trying to start a square dance?!?! He's from Italy!