I like the idea of extra content after you beat the game, but not so much in a NG+ format. My personal favorite way of handling this (for an RPG anyway) is the way Fire Emblem: Awakening does; you can save after you beat the final boss, and when you load up your "clear" data, you're at the start of the final chapter, but there's a bunch of sidequests etc. that are open now. So you can go and beat the final boss and watch the end again, or you can mess around with the extra stuff.
That's the only way I'd be okay with it, personally. :/ I love playing games more than once, but if you're superpowered at the beginning, it just makes all the combat tedious IMO.