See Twezie's post. It isn't catering solely to hardcore players, in fact the primary reason for the feature- as in 'literally every game ever'- is to save the game after an important event. You could crash soon after doing really well in a battle, or simply exit the game quickly without remembering to save it. Then you would be frustrated, especially so if it had been a hard won battle that you expected to lose.
That said, of course more options are better, and though autosave might be particularly beneficial during early access when the game is less stable (not just for the player but also potentially for the player to pass on the save file to the devs to figure out bugs and crashes), disabling autosave entirely should be a feature. If not now, at least in the final game.