I HATE HATE HATE KQ7's chapter system. Exo has elaborated most of the reasons above, which I pretty much agree with completely. Also, in KQ7, the whole reason they did the chapter system was to essentially replace the need for manual saving. Eventually they restored the ability to save manually in a later patch, because it was such a bad decision to remove it originally, and so many people voiced displeasure at it. You only had a "save and quit" option, which REALLY made the game feel different (bad different) from the previous entries in the series. You couldn't create savegames whenever you wanted, so in order to allow the player to reply sections again, they staged the arbitrary "chapter" checkpoints. The chapters were also incorporated into the narrative somewhat, in order to create little cliffhangers within the story. I don't have a problem with that idea in and of itself, as it can enhance the narrative, but in KQ7 it always felt artificial and immersion breaking to me, like they had written the story, and then decided on a chapter system, and then weakly shoehorned the story to fit that format. It just wasn't handled as well as it could have been.
Also, you should NEVER be able to skip to the end of a game without playing the first parts like that. It was a ridiculous design decision. At least with Telltale, we wouldn't have to worry about the ridiculousness of playing the chapters out of order. But yeah, in general, chapter system = FUCKING TERRIBLE DESIGN IDEA for a KQ game.