After the iPad first took the tablet market by storm in 2010, competing vendors tried to find ways to differentiate themselves, Mainelli reasoned. "So they put in USB ports, HDMI ports and [storage] expansion slots," he said. "In many ways, I think the slots are a throwback to expectations people had around their PCs and the need for additional storage and more inputs/outputs."
Some customers do demand storage expansion and other slots, but mainstream tablet users "are rapidly moving away from them," Mainelli said. "People use their tablets differently than they use their PCs, and cloud storage is definitely part of this evolution. Smartphone usage impacts this, too.
"Dramatically fewer people need to get an image off a storage card in a camera and into their tablet, since most of that is happening through services like online photo sharing sites, such as Facebook and iCloud," he said.
IDC analyst Ryan Reith said that while storage expansion slots in tablets may have been at one time a major threat to enterprise security, some companies are installing system-wide mobile management software that can disable external storage.
Even so, some companies have to devise stop-gap measures to prevent workers or visitors from using expansion slots, like putting tape over the slots, Mainelli said.
Samsung defended its use of SD card slots, which show up in Galaxy Tab 3 tablets, as well as Galaxy Tab 2 devices and the Galaxy Note phablets. "Samsung has actually offered expanded storage through SD card slots for a while now," a spokeswoman said. "We want to offer consumers the additional space for storage."
Microsoft didn't respond to a request for comment on its use of storage slots in Windows 8 tablets, including its own Surface Pro and Surface RT machines. Mainelli expects both Microsoft and Samsung to continue to offer a storage expansion slot as a way to differentiate their hardware.
"Microsoft's motivation [for storage expansion slots] is that they are really driving people to use their tablets as both a PC when they want and a tablet when they want," Mainelli said. Meanwhile, Samsung makes many tablets and other products in different sizes and with different features, meaning some future devices will have expansion slots while others don't.
In a recent TV advertisement, Dell compares its 32GB XPS 10 tablet (running Windows RT and selling for $399 at the moment) to an iPad with the same storage and a $599 price tag. The ad calls attention to the iPad's inability to take an SD card since it has no SD card slot, unlike the XPS 10.
Mainelli isn't sure how important the SD card slot will remain for Microsoft. He's one of many analysts concerned about slow sales for Windows RT tablets, although that may be due more to its operating system than the hardware.
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