I strongly agree with you here. That's my point as well. Not headphone jacket, as I said I even noticed it exist in last 3 years, but lack of innovation. This really annoy me. It seems to me this year iPhone is a kind of "gap wait" (sorry I don't know if there is a word to say that), a model Apple released just in order to make us wait for the next big one, with new design and really relevant news next year, when iPhone makes 10th anniversary. This is not good.
But, look, I don't see just Apple doing this. All manufacturers are quite boring last years. Even Samsung (and I say this looking for my S7 Olympics Edition); more processor, more software gimmicks, better camera, better battery (but, sorry, still not a par with my 6 Plus), theoretically better screens with bigger resolutions (but, really, do you really notice any practical difference between the "I-don't-know-how-old" retina displays resolutions and these world cracking 4K screens Sony want to convince us is the unique 21st century experience??) and... What news? What really news? I'm a bit old, so I remember choosing in the past between Sony Cli? and a lot of Palm devices, then between PalmOS, Windows Mobile, Symbian, all with different main points and downfalls and extremely different designs.
Today what do we have? Here, in Brazil, all Samsungs (the only manufacturer which really do care about this huge market), all iPhones very late and very overpriced (our iPhone is the world's most expensive every year, for the last eight consecutive years), some Motorolas, some overpriced LGs and, now, some Chinese brands. And that's all. All almost the same. So, lack of news is really a very tough question for me too. I just don't see it as a "just Apple" problem.
And relax, for me at least we are not fighting, in any meaning. I won't ever defend Apple or someone else. I just like to debate ideas, nothing more than this.