Divinity 2 is neither long nor short for such a RPG... the main-story could probably get finished in very little time, but with the sidequests and the "killing of all monsters" it's about what to expect from a game in that genre.
It's not like Morrowind, for example, where you have a slooooooowwwww walking speed... if it takes you five minutes to walk from one end of the village to the other... it's no wonder the game feels loooooonger.
