Sorry to disagree. First of all, Apple has taken the Ethernet port from my MacBook PRO, requiring me to use an adapter. Now why would they do that if it were far superior to Wifi, as we both agree is the case? Apple also prevents me from connecting my iPad, iPhone and iPod Touch to Ethernet, even with an adapter. So, same question -- why would Apple deny me the ability to use the "superior internet" if I chose? The only Apple products that still have Ethernet ports are desktop Macs, and the TV, all of which are meant to be installed in fixed locations. So there's the common connection -- Apple has removed the Ethernet connector on all mobile devices. Now maybe at one time, listening to audio was once the exclusive provence of the couch set, putting on an album and sitting back to absorb the music for 20 minutes. Or sitting in an easy chair a couple of feet away tethered to an amp, listening through headphones. But no more. Audio is mobile. It's on our iPods, our iPhones, iPads, and Macs. People are increasingly playing back music over bluetooth equipment, at home and in their cars, able to walk around and do other things as they listen to music. They are mobile. And while it's easy to say a wired headphone is not a big deal with an iPod shuffle which can just be clipped to a person's clothing, that convenience starts to disappear when a larger iPhone must be strapped to an arm, or worn in a belt holster, to say nothing of an iPad, a MacBook, or an iMac. If someone needs to listen to music privately, that shouldn't necessarily mean they need to sit in place to do it. Or unplug if they need to move around, or even carry their device with them as they move.
So for starters, my position is not that BT is "the logical choice of the future" but rather wireless is the future of audio, as it is for everything. Right now, BT is the standard, who knows what it will be in the future. Unfortunately your argument on all fronts is grounded in what is possible today. Yes Wifi is still lagging behind Ethernet, but because wireless internet is in demand, great strides are being made to close the gap. But why would anyone opt for an inferior experience? Obviously, it's for the convenience of portability. Isn't it amazing what people will tolerate in order to use Wifi, or LTE, to say nothing of what people were willing to tolerate in 1998 when wifi was introduced? And the same is true for for audio. So what's the difference? Wireless audio is slow to improve, and it's expensive, mainly because the demand is so low. And why is the demand low? Because people don't have to look for another alternative, because every product they buy has an inexpensive, ubiquitous standard that's been around for over 100 years. Ethernet has never been inexpensive for the average consumer, who typically opted for much less expensive and reliable dialup modems which were the standard at the time. And when wifi came around, the commercial demand for conevenience drove the price down and improvements up. Necessity is the mother of invention, and until wireless audio is in greater demand, prices will remain unaffordable for most, and improvements will be marginal. Giving customers a reason to switch drives development in wireless audio, which in the end is what's best for everyone. In the meantime, anybody who wants the absolute highest quality audio they can get out of an iPhone, will have an adapter, just like I do for Ethernet on my MacBook Pro. And one day, just like Wifi will offer me the same experience as a wired Ethernet connector, so will wireless audio over the wired 3.5mm connector, or Lightning connector, and everyone will benefit from that over being tethered to something with a wire.
And again, I'm not pushing BT on anybody. If Apple does this, it's Apple who's trying to move people toward the inevitable future of audio. I'm just trying to look at it from their perspective, and address the argument that there is no improvement over the 3.5mm audio jack, which is clearly not true -- being free of wires is a massive improvement, and perhaps the only justifiable one in consumer audio. The tradeoffs involved at any point in the development of a technology are the only issue. But the end result is inevitable. If Apple does this, they're doing it for the same reasons they've been perceived as dropping legacy technology prematurely over the years -- to speed the development of a superior user experience. And wireless is that new standard for audio.
You're not thinking "4th dimensionally" as Doc Brown would say. Well at least 3 dimensionally. It's not about the height of the 3.5mm connector, which currently limits the thickness of a device to about 5mm when you factor in housing and case thickness. The iPhone is a good 2mm away from crossing that threshold for the connector thickness to matter. But that doesn't mean removing it won't allow them to make the iPhone thinner. The 3.5mm jack takes up a whopping 184 cubic mm inside the phone, and only provides a single function, which happens to have 2 redundant ports capable of much more than audio. What happens then, is that volume is reclaimed by spreading out other components, which allows them to be thinner, and thus the entire phone. Or alternately, and more importantly, they are able to add additional features, or battery capacity, which they previously didn't have room for without increasing the size of the phone.
Of course the benefits of adding any additional battery should be evident, but in terms of the trade-off for the 3.5mm adapter, the gains would help offset battery use for those already using BT, and make using BT more palatable to those who don't use it presently due to the impact on battery life. And considering Apple has consistently made gains in battery life since the first iPhone, even reducing battery capacity in the 6S while retaining the same battery life, I have to think Apple wouldn't do this if there wasn't a significant improvement. For those who don't don't want any hit on battery life, there's an adapter, and they will still benefit from much longer battery life.
For me waterproofing is the least of the concerns here, and I'm not even sure why anyone is mentioning it in connection with the 3.5mm jack removal, however, it can only help. The main benefits are going to be adding features, while reducing redundant technology, improving battery life, promoting development and improvement of wireless audio technologies, resulting from increased competition which will lower the price of these new technologies, which ultimately benefits consumers in the form of more choice, cost and convenience. And all of this without changing the size of the iPhone significantly, allowing Apple to remain competitive in the marketplace.