One big technical reason for this was actually the file system. Back when phones came with various types of sd-card support, they only had a few gigs of storage. fat32 was enough and was supported everywhere. But fat32 had some file system limitations and when sd-card sizes grew over 4gb there were comparability issues since windows was limited to fat32 and ntfs. I can imagine the support hell when a user couldn’t mount the sd card containing photos on his or her computer.