1. Shielding - Never had any problems in any phone I've ever owned. If shielding is an issue in the "new & improved iphone", then add a damn 1/10th of a mm and put some shielding back in. I'll trade a bit of imaginary interference for bluetooth
drops & pairing difficulties any day.
I guess you never sit your headphones on a busy desk with cables, laptops, etc. then. I had Sennheiser HD-25 II wired studio monitoring headphones with one of the best-shielded cables made for headphones (steel and very thick) and the EM emissions from the IGP on my laptop (a Westmere i5; this was years ago) would be very audible over the music streaming from my MP3 player (this was before I got a smartphone with enough storage and CPU to play music). Newer Intel procs are better at reducing EM, but cheap headphone cables will still pick up emissions several inches away from a desktop with a Skylake i7 in my limited testing. These CPUs will happily spew harmless electromagnetic emissions that get converted into arbitrary sounds by your headphones when the conductor in your cable picks them up.
Also, the only bluetooth drops and pairing problems I've had in recent years were all on Android. I moved from buying Android phones (numerous, from 3 different manufacturers, all had the same problems with BT) to an iPhone 6S Plus, and I have not had a single BT dropout, not a single one in like 9 months. And pairing always succeeds immediately.
For my desktop and Windows laptop I use an Imperial BART 1 bluetooth transceiver (with aptX Low Latency) as an intermediary, with the sound being sent to the BART 1 from the motherboard's S/PDIF digital (TOSLINK) port. So the entire audio path is digital. 24-bit 48 kHz, too, which is better than the 16-bit 44.1 kHz that 99.9% of the people are using, and not audibly distinguishable from even higher bitrates and sample rates in most studies (the law of diminishing returns).
This allows me to have two pair of headphones, total -- one I keep at work and one I keep at home -- for all my headphone needs across desktop, laptop and smartphone. And both headsets double as a serviceable mic to take phone calls, either over Skype or the cellular network. And I never have to tangle with cables.
2. Finicky jacks - this is perhaps one of only two points that I think has some credence. I've had a couple of finicky jacks myself but you know what--a quick squirt of contact cleaner solved the problem perfectly. Want to talk about finicky? Bluetooth
pairing on some devices. You know what's even more finicky? When your BT headset battery starts to wear out and you can't replace it. Wired headsets have a much longer lifetime than BT headsets.
I only buy BT headsets with user-replaceable batteries. What kind of junk are you buying that doesn't? Beats? People actually think Beats BT headsets are good, you know? It's embarrassing and a disgrace to actually good bluetooth headsets, like the BeoPlay H8.
BT pairing issues are basically non-existent if both devices support BT version >= 4.0. Latency is not a problem if both ends support aptX Low Latency (it sits around 30-ish ms with very low jitter, and it's not detectable by most users, even when gaming, even while focused on it.) Not all BT versions and not all BT equipment is created equal, though. Android is an absolute cesspool of crappy BT stacks. Avoid it like the plague. Literally anything else is better.
Also, I've had plenty of wired headsets fail me over the years. Cables break; connectors come loose from the cable; pads start to peel off; and on and on. You can argue that only shitty wired headsets break like that, but I argue that only shitty BT headsets break the way you say they do.
3. Universal plugs - While it's true that there are variations of the 3.5 mm plug, I cannot remember a single time in the past 15 years a time when I plugged a 3.5 mm headset into an apple or android phone and it failed to work. I can remember plenty
of times when I couldn't get bluetooth to pair.
Stop living in the past. BT pairing issues are dead unless you buy products released to market 4 or more years ago. Buy modern kit and the problem is 100% GONE.
4. Unencrypted data - The second fair point. However, device manufacturers like square have started encrypting their data and this is only applicable to a tiny fraction of phone users.
Just because not all digital alternatives to 3.5mm are encrypting now, doesn't mean that staying on a protocol that will always (by design) be unencrypted is necessarily a good thing. Crypto used with the purpose of providing users greater privacy and protection is a good thing. We just have to take back control from manufacturers and media cartels trying to use crypto against us (DRM). That's a political battle, whereas analog vs. digital is purely technical.
5. Cheap DAC - This may be true, but my wired headsets are unequivocally better audio quality than any of my bluetooth headsets.
Sounds like you haven't invested in great bluetooth headphones, then. And besides, we're not talking JUST about Bluetooth. Bluetooth audio (with aptX or even AAC) should be high enough fidelity to satisfy the vast majority of consumers, and will sound as good as or better than the cheap 3.5mm analog headphones they bought for $40 at Best Buy, depending on how much they spent on their BT headphones (generally speaking, to get BT audio of the same quality as a wired headset, just add about $100 to the price tag). But for the real pros who want super high fidelity, there's Lightning, USB-C, and other RF-based (non-Bluetooth) wireless protocols that are available at varying degrees of support. Don't worry; the industry should eventually start to standardize or at least offer cheap dongles to ensure wide compatibility. It'll just take some time.
Now sure, you could say you don't want to have to pay $100 extra for your headphones. But you also get a freedom of movement and freedom from cables (which, when they bump into things, make very audible and irritating noises interfering with your music) that you don't get with wired, so it's not purely a replacement of one thing with another with no advantages.
6. Thickness - I don't need a thinner phone. I want a phone with better batter life. Hell, increase the thickness and give me some more battery life.
I agree with this. Buy a Moto Z Force when it comes out. Those things are shaping up to be very thick, and can be made even thicker by snapping an external battery onto the back. But it's still a valid argument that by removing the 3.5mm port, you're opening up some room inside the phone for more battery in the same space.
Net net--I will not upgrade to a phone that is missing a 3.5 mm headphone jack anytime soon. I am sure it will happen int he future, but not in my near future.
Since I'm completely converged on the bluetooth revolution already, the lack of a 3.5mm jack will not be a barrier at all to my next smartphone purchase. Rather, quality of the OS's bluetooth stack will factor in tremendously. Until Android fixes their broken bullshit, I basically have no choice but to buy iPhone.