Since first using it, we've been puzzled by Windows RT. In a world with Clover Trail—a chip that offers adequate performance and ARM-like power consumption while retaining compatibility with all the x86 software that's out there—a version of Windows for ARM chips seemed to have little value.

One by one, the PC OEMs seem to be having similar thoughts. Asus was typically outspoken about it, saying that Windows RT was "not very promising." Samsung put its Windows RT tablet on ice in March. Lenovo replaced its ARM Yoga 11 with the x86 Yoga 11S. And now Dell appears to have given up on the platform too, with its XPS 10 tablet now showing as unavailable in its online store.

This last loss is perhaps the most painful. The Dell tablet was aggressively priced and had been the star of one of Microsoft's amusing Siri-trolling advertisements, but it looks as if even this promotional effort wasn't enough to keep the thing around.

With Dell gone, Microsoft is now the sole vendor of Windows RT systems. Its Surface tablet is the only ARM Windows machine still on the market. Next month it will be joined by its newer sibling: Microsoft is slotting the Surface 2 above the Surface to have ARM systems available at $349 and $449.

None of this means that third-party interest in Windows RT has dried up entirely. It's possible that with the October 18 launch of Windows 8.1, we'll see a second generation of Windows RT hardware from other vendors.

But the big problem with Windows RT will remain: for more or less the same amount of money, you'll be able to buy an x86 system in more or less the same form factor with more or less the same battery life and probably better performance. Plus that x86 system will run "legacy" desktop software. Even if you only want to run touch-first, tablet software, having that fallback option just in case is no bad thing. It's not that Windows RT is bad, per se. It's just that Windows 8 is better.

This issue becomes increasingly acute with Intel's Bay Trail processors. While last year's Clover Trail parts were striking insofar as they demonstrated that Intel could compete in the same low power ballpark as ARM, Bay Trail shows that not only can Intel compete, but it can produce parts with strong performance while still only sipping power. Sure, Surface 2 looks nice and the purple Type Cover looks glorious, but one can't help but feel that it would be nicer still with a Bay Trail of some kind instead of a Tegra 4.

So why go with Windows RT? The question has been asked since the platform was launched, and Microsoft has never really provided a good answer. If Intel had never got its Atom act together, then there was an easy, straightforward answer: price and power consumption. Buyers would have a simple trade-off: ARM Windows for cheap, long-lived ultraportables, x86 for everything else.

But Atom now works, and that means x86 can do it all. The question remains unanswered.

(It's worth noting that developing Windows RT is valuable independent from selling it. The development is necessitated by Windows Phone, which is also an ARM Windows variant.)

The unanswered question is not, however, completely unanswerable. Windows RT does have some advantages when it comes to security and crapware. That incompatibility with x86 software also confers an incompatibility with x86 malware. For certain demographics—schools, non-tech savvy users, security conscious corporations—that could be appealing. This is one of the things that has drawn people to the iPad (albeit with mixed results). Confidence that you can never screw a system up is a desirable thing, and it's certainly harder to screw up Windows RT than regular Windows.

But perhaps hamstrung by the fact that Microsoft doesn't want to cast x86 Windows as vulnerable, the company has done little to promote this particular angle. It also hasn't supported the form factors to truly capitalize on this approach.

So once more, the question is just out there. Why Windows RT?

Until Microsoft can provide a compelling answer to the buying public—a reason to explicitly choose Windows RT and not its more capable big brother—it's hard to see OEMs and consumers alike being any more willing to ride the Windows RT train a second time around. Without a good answer, Atom products are almost always going to be the better choice.

And if Microsoft can't, or won't, provide that answer, perhaps it would be better off killing Windows RT off altogether.