Update 12/05/2018: A representative for Esports Arena -- the company responsible for designing Walmart's Overpowered desktops -- has reached out to inform us that the machines were "briefly removed" from sale in order to update their product information, but they are once again available for purchase.
Though it's tough to say precisely why the company made this decision, the most likely reason is the negative publicity that's surrounded the machines since their launch.
Not only were the desktop rigs, dubbed the DTW1, DTW2, and DTW3, lambasted for their questionable value, but the low quality of some of their internal components has been called out by several major tech websites and YouTubers.
Tech personality Kyle, who runs the Bitwit YouTube channel, put together a first impressions video examining Walmart's $1400, GeForce GTX 1070-equipped DTW1 desktop.
Though he did not benchmark the machine's components in said video, he did draw attention to the rig's poor-quality micro ATX motherboard and power supply; noting that they were obvious cost-cutting measures on Walmart's part.
The cable management also looked to be less-than-ideal (though it's not the worst we've seen), and some critical cables -- such as the GPU's power cord -- were unattached when the system arrived on Kyle's doorstep.
In the end, it seems clear that for Walmart, the machines just weren't worth the bad press they were receiving. However, the company is still selling its full line of Overpowered gaming laptops.
Whether or not those will be pulled from sale as well remains to be seen, but for now, they seem to have flown under the tech community's radar.