I don't doubt that having a desk with a built-in cable tray, plus cable anchors that you can stick anywhere on the desk, would be convenient. But I do think making the entire desk magnetic is a long way to go for the convenience.
Then again, Secretlab's Magnus Metal Desk with Magnetic Ecosystem is targeted at gamers who tend to prize features like built-in LED mood lighting, and would take the time to ensure their desktop is perfectly level, so perhaps market research has done their job here.
The desk can be kitted out with magnetic cable management anchors, magnetic sheathes that cover the legs and a magnetic headphone hanger that sticks to the desktop's underside. The surface of the desk can be covered corner-to-corner with a "Mag-Pad" magnetic-backed leatherette surface with contrasting top stitching.
One glaring design flaw I see is that the cable management tray lid was designed for cables, not fingers. You're meant to open and close it by holding onto the sides only, though it seems more intuitive to grab it somewhere in the middle.
Here's the desk's "demo guide" video:
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The desk will run you $582 with the cable management accessories and the Mag-Pad, and without the headphone hanger; the pricing for the latter has not yet been announced.