That all changed when Volition parent company THQ died and the developer passed on to Deep Silver. Every mod they created was the result of finding the game's nooks and crannies and exploiting them. For a long time, Saints Row: The Third and IV mods had to created by fans who basically hacked into game to create new content. That world is still rigidly defined though, because Saints Row IV hasn't allowed PC players to natively mod the title.
When it comes to limitations, Saints Row IV doesn't have many within the confines of its world. This culminated in Saints Row IV, where you played the President of the United States, using your Matrix-style superpowers to fight against an invading alien force. In ever-escalating fashion, the series allowed you to look and play how you wanted.
Is there something you think we should be reporting on? Email it tore itself away from the shackles of Grand Theft Auto, the Saints Row series has always been about freedom.