For PC gamers, the experience for games tends to last beyond what is contained in the original game. Take Skyrim, for example. While this game has tons of content on all platforms, you’ll find thousands of mods out there that enrich and even extend your gaming experience (okay, some of them might not exactly enrich your experience, but most of them do). So naturally, with any successful game, people will work on mods, and hope for an official SDK from the developer.
Borderlands developer Gearbox recently revealed that they had considered releasing an SDK for the first game. However, they ultimately decided that they could spend a year working on that, or starting on a sequel. Ultimately they decided that modders were already accomplishing much of the work without one, so their time would be better invested in DLC and the next game.
So what about Borderlands 2? The company has said that they are once again going to forgo the distribution of an SDK. However, they are encouraging players to mod the game to their hearts’ content.