Dongles slapped on after the fact are a poor design. They ruin the ability to hold the device one handed, the ability to pocket the phone with the module attach

Dongles slapped on after the fact are a poor design. They ruin the ability to hold the device one handed, the ability to pocket the phone with the module attached, or add substantial bulk to cases that must be redesigned for every variant of phone. USB is a decent electrical interconnect and API standard... But not a good cellphone mechanical modularity standard.