There are options; NVMe and CFExpress cards exist. But they're large and create inefficiencies in the phone shell (even M.2 2230, when you take into account the mounting mechanism), and I doubt that people are going to pay that kind of money even when they currently pay it for onboard storage.
It's been a long, long time since I couldn't fit all the apps I wanted on the phone storage. My SD card is mainly for multimedia files, and it's plenty fast for that purpose.
The only performance limit I've hit in recent times was because it was exFAT, not because it was an SD card.
> There are options; NVMe and CFExpress cards exist. But they're large
Ignoring SD Express as a failure to launch, UHS SD cards can be plenty fast if they're designed to be. A hundred megabytes per second is not a significant bottleneck if individual IO operations are fast and it can do many of them.
Also there was that XFMEXPRESS form factor if manufacturers wanted to put an SSD socket into a phone. "card size is 18x14x1.4mm, slightly larger and thicker than a microSD card. It mounts into a latching socket that increases the footprint up to 22.2x17.75x2.2mm."
> and I doubt that people are going to pay that kind of money even when they currently pay it for onboard storage.
That's the real killer incentive, that you can charge huge amounts per terabyte and also force people to buy higher-end phones just to get the ability to buy more storage.
As opposed to the user spending $40 for a 512GB sandisk extreme, and giving the phone maker no extra money.
You have to remember that a current microsd cards is just a general purpose micro-controller and some (probably SPI) flash in a plastic case.
As mentioned, random I/O tends to fail, but the other tradeoff here is that fast microSD card slots tend to get extremely hot. Not necessarily "failure" hot (stuff like the ROG had issues from other parts), but uncomfortable to hold, depending on where the thing is going to go.
> As opposed to the user spending $40 for a 512GB sandisk extreme, and giving the phone maker no extra money.
The thing is, price anchoring is a thing, and people are going to look at a phone that costs $400 and needs a $40 Extra Thing and a $500 phone and go "the latter is easier".
Oh definitely. I would too. I dream of the price being only $200/TB.
The biggest storage upgrade for a normal iPhone is +384GB for $300 (Oof). If you upgrade to the Max model you can get +768GB for $400.
A Galaxy S23 can get +128GB for $60, a Galaxy S23+ can get +256GB for $120, and a Galaxy S23 Ultra can get +768GB for $420.
A Pixel 8 can get +128GB for $60, and a Pixel 8 Pro can get +896GB for $400.
If you include the price increase of better base models, to get access to bigger options, then $700/TB is a good ballpark figure.
I think this pricing is a little bit better than when I last looked, but it's still very bad.
The availability of >512GB is growing but still flaky and usually requires extra expensive base models. While in comparison microsd has had cheap 1TB for a good while, and 1.5TB for $150 becomes available later this month.