The bluetooth implementations all suck. My $40k car is about as reliable and predictable from a bluetooth perspective as Chinese knock-off Jawbone copycat from 2007.
Who decided to use such a flaky protocol for audio and such, and then remove the reliable connection?
Add to that great complexity at Layer 1, and constantly changing specs. Bluetooth 1, 2, and 4 are all radically different than each other.
Compare with WiFi, which only has to do one thing (Layer 1-2). Cellular is much more complex, but that's why releasing a new phone involves endless rounds of (usually mandatory and very strict) carrier certification.
I want non crappy Bluetooth mice that don't require a separate USB dongle. :(
Edit: To be clear, I'm sure ethernet cables are an entirely different thing and there's actually a very good reason why wireless makes everything more complicated. But, well, maybe that's one of the reasons people would like to stick with wires.
Everyone gets what they want, except for the end user!
Even though wireless transmitters have gotten a lot better than previous times (in the 1980s one of the Spinal Tap spoofs was getting radio interference in their wireless guitar system if I recall correctly), now using similar frequency bands wi-fi does with proprietary protocols from what I see (definitely not Bluetooth!)... you still see reviews of reliability problems in some circumstances. You'd definitely want to carry around a standard guitar cable as a backup if you have one.
Moving parts and physical connections are fragile. Wireless connections solve that fragility. Agreed that pairing sucks, but that's a solvable problem.
The music industry standard for instrument cables is 1/4" TS for unbalanced instrument audio, 1/4" TRS for a few things like monitoring headphones, and XLR cables for most everything else. XLR in particular is a very durable system, unless you get a very badly made XLR cable or jack I would never call this system "fragile". Even 1/4" is quite an improvement durability wise over 3.5mm.
XLR is not exactly a very portable jack, but a mini-XLR jack does exist -- not as portable as TRS 3.5mm, of course. But if increasing jack durability is such a concern on a more portable device, this connector is an option. Same with using 1/4" TRS, this is a connector which has the advantage of having more headphone options with this option built in (most headphones marketed for studios should be 1/4" TRS or at least have that option).
None of the above are as portable as 3.5mm and I think this connector is "durable enough" to where I doubt it is such a priority for most phone consumers to give up some phone thickness for better durability. But in professional music applications there is a reason why 3.5mm is relatively rare.
I mean, at some level, come on and use your imagination. People riding the metro don't always have total control over getting their belongings situated properly when the train's packed and there's a lot of bustling around. I assure you this experience is not unique to me.
So, I guess there are tradeoffs -- and fixing pairing means everyone can enjoy freedom from one more wire, while keeping on using a wire means we keep adapting our behaviors around a wire.
And price: a jack is dumb tech and cheap (cheap anough that I always had about 10 extra jacks of all kinds with me when I was doing a gig).
But to be fair, wireless transmitters/receivers do exist for musicians. They don't use bluetooth ofc, but that means that the latency can be bearable with wireless. It's made for live playing though (freedom of movement), no point using that in studio