I do wonder how true it is that the "put microSD cards in your computer" market is smaller than the "put SD cards in your computer" market.
If I think of the devices that I have microSD cards in (Nintendo Switch, Steam Deck, Windows tablet, phones), they're all devices where the microSD card just lives in the device and only gets removed when I'm upgrading the device. Or I guess there was the time I installed CFW on my 2DS XL.
On the other hand, I take the SD card in and out of my camera much more often, despite it getting less use than the aforementioned microSD using devices.
Not to mention most microSD cards are sold with a microSD -> SD adapter, so to me it feels like if you're going to do only one adapter, you'd do SD.