Headphone jacks are still ubiquitous, work well, and aren't overly large. There's also not really a significant downside vs other ports. USB-C beats previous ports because it's better:

• micro-USB - destroyed cables and ports
• mini-USB - uncommon
• micro-super speed - even less common
• iPhone lightning cable - broke easily, unique to Apple

Moving to USB-C gives you:

• better port - I'm pretty sure it'll outlast most of the above
• faster speeds
• more features
• high speed charging

Basically, the only downside is having to buy more cables (and the annoying difference between cable capabilities), and a little higher cost to include it in a product.

With the headphone jack, there's really no objectively superior alternative. USB-C requires a dongle or USB-C specific headphones, and there's not really a change to audio quality. If you want to charge at the same time (like you showed), you need an awkward dongle with half that'll go unused most of the time. Yeah, it works, but it's a solution to an artificial problem. They could just include an audio jack instead...

My phone has an completely excessive 512GB of storage

Ok, and how much did that built-in storage cost you? Would you have preferred a smaller amount of storage if it meant lower cost, and have the option to expand with a micro-SD card? With Apple, you'd pay $100 to bump to 256GB and $200 more to bump to 512GB. So you're paying $300 to go from 128GB to 512GB. I could buy a fast, 512GB microsd card for $55 (or slower drives for $35).

And what happens if you switch devices? Let's say you decide to go Android, now you need to figure out how to get your stuff from one phone to the other. With a micro-SD card, you just move the card. Or if someone wants to get a copy of photos you took, just copy to a micro-SD card and give it to them.

If you don't want to use it, you don't need to, but micro-SD ports are small (often paired with the SIM slot) and inexpensive.

Having those convenience ports doesn't cost you anything and you can ignore them if you want. So I really don't see a downside to manufacturers keeping them, and it just gives users flexibility. I actually never used the SD slot on my old phone, but I was glad it was there. I would've used it if my phone lasted longer than 3-ish years before running out of software updates.

If someone comes up with a better alternative to SD cards or headphone jacks, sure, replace them. But current phones merely lost functionality. Maybe they could have a version w/o the port that has a bit more battery, that would be a good compromise for losing a port you may not want. But just eliminating it while it's still popular is stupid.