As others pointed out, you can get USB-C->3.5mm stuff. They make a large variety of such (everything from tiny dongles that are barely more than the 3.5mm jack+strain relief to full blown DAC/amps and everything in between).
It is a shame that they didn't keep the 3.5mm (or go to 2.5mm) port and use it for everything so that you could keep using headphones and aux cables, plus have a port that you can't insert incorrectly, that would be even easier to make robust than USB-C or Lightning (since cables can spin, and right angle cables even further limit strain compared to right angle USB-C cables).
I also think its ridiculous that they're shoving little lithium ion batteries in wireless buds instead of using capacitors (that could charge faster and won't wear out as fast). Ditto for stylus doing the same thing (and the only reason they should even be active at all is some of the wireless/bluetooth control features).
The next major stupidity is them having gigantic camera bumps instead of just making the camera bump entirely separate (make it so they can slap on via magnets and pogo pins or magsafe). Gets rid of the need for hole punches or other, makes the phones more unified, makes the camera more flexible (i.e. can have it face either direction, use across multiple devices - you can buy a single camera module instead of them cramming 3+ cameras in every single device). Easier to secure for privacy (although small size would have presented some issues in that regard, but those issues still exist since can buy such cameras anyway). Could also offer "tough" versions (think action cameras), or heck full blown camera systems, and less constrained. It would make phones less fragile too, and free up space for bigger batteries and/or making the batteries more accessible again.
i think - but don't know - that microSD slots were removed because they are not watertight. Another port is another point of failure, and people are getting dumber.
Which sucks donkey bawls because it was a great way to carry playlists without loading up the phone, and imho Android music players all kinda suck when it comes to things like playlists and shuffle.
As for the pin-jack, i've kinda gotten over it, because i found this chinese headset thingie that costs under $30 and is absolutely phenomenal, from the quality of sound, to the bluetooth functionality, build quality, battery life - you really couldn't ask more of a product that costs 4x as i paid.
Still, some people - those who invested in high-end wired headphones - must be really fuming right now. (and those who spend $$ on high-end bluetooth stuff i really don't care about because you gotta be a moron).
But, it's a move away from your phone being a portable music player, to more of a multimedia jack-of-all-trades thing, sacrificing quality for convenience. I also understand that a big power-amp that can deliver a strong bass over high ohms will rekk your battery life, so there's another thing they probably wanted to avoid .. bad publicity, whether deserved or not, is still bad publicity.
edit; posting in Naer thread.
That's nonsense as the microSD was always in the SIM card slot area, so SIM cards should have similarly made them prone to water damage.
The industry fed all the tech media sycophants nonsense that the memory cards were a major source of issues (effectively being both full of crap and blaming customers), and sadly they regurgitated that crap for years (even Anandtech used to push that BS, with very few questionning it, frickin Linus of all people actually seems to have come around on how BS that was although he had been still saying it not that long before). I don't even think the "saving money" argument flies since again, it was in the same spot as the SIM cards so they already had to put the space in and even the wiring (to support the SIM cards).
The reality is it was to push people to cloud services (and the people that need for or just have insecurity about not having enough storage to upsell to pay a lot for extra storage - i.e. Apple puts out the low capacity model and touts its price but expects most people will go to tier 2). That also primed people to be conditioned to not worry about accessing content like physical media (i.e. subscribe to services where you effectively don't actually own anything any more).
No one but Head-Fi weirdos are trying to use big full size high ohm headphones with phones, so that's not even a consideration. Heck, many headphones (like Beats) had their own batteries before they even removed the headphone jack. And the Head-Fi weirdos were also using amps and other as well that had their own batteries. They've since moved onto spending thousands for dedicated portable audio players (I guess, there's tons of those in the market now, but I have literally never seen a human use one in person). I don't think the megabuck headphone people fumed at it, as they were already looking to use USB out to a DAC and they'd been doing everything possible to bypass the alleged poor quality analog headphone out of like iPods and iPhone anyway. It was normal people that buy cheap headphones because they just want something cheap that was doing what they wanted it for.