Re: Saw it coming, just didn't care.
As for SD card... I can't go there with you. It feels too much like saying you want a floppy drive on an internet connected device. 256GB on phones these days... Do you really need more?
This really isn't a question you should be asking since it seems you use iPhone only. So you've already compensated for it. But for android devices similar to a pc, the real argument is the difference between only one internal soldered storage vs an additional removable storage. If I use the floppy drive logic, it will be only one internal soldered floppy drive vs an additional removable floppy drive.
A removable medium will always have these benefits.
Case 1, flexibility in file transfer. Let's try transferring 256GB of files to your phone. Let's go with the cable, darn now you can't use your phone for 1-3hrs unless you wait near the pc. Let's try with the cloud, what? that's 3-7hrs of waiting near a wifi or I get a +$500 bill on my data bill. Oh wait, you have an sd card? Transfer your files to the sd card, then come back when it's ready. You gain the freedom to use your phone without waiting.
Case 2, secondary backup. Oops you broke your phone after taking a long day worth of photos in the rural area with no data signal. Now you can't turn it on. At least you still have your last cloud data backup. Oh wait, you saved the photos on the sd card? Great, it'll still be in there. Just plug it in to your pc and all your photos will still be there.
Case 3, the ability to upgrade. 256GB phone meet my quadruplet (4x) 256GB media collection sd cards. Wait, 512GB sd cards are finally out? Buy, insert, upgrade. You can never have too much space, only too little. (ok ok this one is extreme. not all phone support 512GB, but the users get to decide at least)