Windows RT, the name Microsoft after calling it "Windows on ARM," or WOA, for months, is the forked version of Windows 8 designed to run on devices powered by ARM SoCs, or system-on-a-chip.

ARM SoCs are the de facto powerhouses that run most smartphones and tablets, including Apple's iPad.

"This is pure speculation on my part, but it seems like they had to make a trade-off with Windows RT," said Michael Cherry, an analyst with Directions on Microsoft, a Kirkland, Wash.-based research firm that specializes in tracking Microsoft's moves. "What we're hearing now about Windows RT is a function of time and how they wanted the thing to behave. It seems to me that the a key goal was to get battery life decent and keep the weight [of devices] down."

Microsoft may have succeeded there by simply getting a version of Windows to run on the power-sipping ARM architecture. But other features or components, Cherry believes, fell by the wayside to meet that primary goal.

"They didn't have to time to get everything in there," Cherry said.