All fair points to varying degrees, I think. My guess is that you may change your mind on some of them though as 3D Touch gets more widely adopted amongst apps. Right now, it is fairly annoying to have to remember which apps do or do not use the functionality — or worse, to guess-and-check each time.
I also expect Apple to tweak certain elements of 3D Touch as iOS 9 matures. For example, I’m in the boat that finds left-side app switching way too hard to trigger. Though maybe for all of this we’re just holding it wrong ;)