The reason is UI.

There's only a limited number of features that you can pack into a few buttons and a 7-segment display. If you want to sell outside the US and need to support the long-tail of non-English languages, preferably without per-country product variants, you can't even label the buttons any more, you have to rely on simple pictograms and icons.

If there's a $1 microcontroller in your device (and there often is), you're very tempted to implement lots of features which cost you almost nothing, but that kind of UI just doesn't really let you do so. Sure, you could add a proper touch screen with a localizable UI stack, with reflowable text and support for displaying Kanji and RTL languages, but that's often more expensive (and less practical) than slapping on a BLE or WiFi chip.