‘Underpromise and overdeliver” is a widely cited mantra in the technology industry, but by its very nature, it’s a business that likes to invent the future, even when the future isn’t quite ready to be invented. And so, we often get the opposite, “overpromising and underdelivering”.

In the spring of 2012, Google announced a groundbreaking new product – Google Glass was a mobile computer in a pair of spectacles, the “screen” floating in the corner of your field of view. The announcement came replete with an obligatory demo video, showing the device literally through the eyes of a New York hipster – notifications, messages and maps magically dropped into view, photographs were taken with a quick verbal command, calls were like speaking to a floating apparition.

Last month, however, Google announced it was effectively shuttering the Glass “open beta” project, and withdrawing Glass from sale. Back when Glass launched, that introductory video seemed fanciful to me – the frictionless ease of the interactions, the smoothness of the graphics, the day-long battery life and so on were years from realisation. The video glossed over the very real technological challenges that would limit the practical use of such a device.

At the time, I wrote in this column of the video’s “reality-gap problem”.

“In their eagerness to show off everything that might be possible in the future, Google has seriously oversold the near-term potential of the device. There are currently some non-trivial limitations on these devices . . . So while the Project Glass video passed the cool gadget test with flying colours, I expect the actual device to be considerably less useful than the clip suggests, leading to a lot of disappointed early-adopters.”

Today, you can take that paragraph and replace Google with Microsoft and Glass with HoloLens.

In an uncanny piece of timing, the same week as Google put Glass on ice, so to speak, Microsoft generated huge buzz with the surprise announcement of the HoloLens, a futuristic headset computer that can seemingly project “holograms” into your surrounding environment, promising to blend the digital world with the real world. It looked like the most ambitious augmented reality project yet, and the announcement came replete with, yes, an obligatory demo video.

Again, there were lots of floating screens and it showed a designer using it to modify motorcycle designs at the flick of a finger, a man building a holographic Minecraft world in his living room, a scientist sauntering around a virtual representation of the surface of Mars, that sort of thing. Some of it looked jaw-droppingly impressive, some of it downright gimmicky.

Minecraft holograms

Technology journalists who were given previews of HoloLens were overwhelmingly positive, while acknowledging the significant caveat that these were highly controlled demonstrations in laboratory conditions. It’s highly unlikely that you’ll be building Minecraft holograms in your living room in the next few months.

But Microsoft isn’t inserting any disclaimers here – they say the HoloLens will be available pretty soon, perhaps as early as this year. Hearing this, I can’t help but think Google Glass and HoloLens powerfully illustrate the danger of “overpromising and underdelivering”.

So why do we see so many companies overpromise like this? We got a fascinating insight into what happened with Glass in a recent report by Nick Bilton in the New York Times. Google co-founder Sergey Brin, Bilton told us, "knew Google Glass wasn't a finished product and that it needed work, but he wanted that to take place in public, not in a top-secret lab".

Reading between the lines, Brin wanted the public acclaim and kudos for inventing the future, without having the patience to actually wait for the future to be feasible. His decision caused considerable strife inside Google, and now we’re seeing the consequences.

Sassy responses

Of course, Google and Microsoft are far from the only companies guilty of this. Even Apple, which notoriously keeps its products under wraps until as close to the point of release as possible, were guilty of overpromising with their ads for speech-recognition personal assistant Siri. The campaign featured various personalities such as Samuel L Jackson chatting away to their iPhones and getting sassy responses back with witty repartee straight out of a 1940s screwball comedy.

Needless to say, you are hardly likely to mistake Siri for Lauren Bacall. As a result, Siri underwhelmed at launch. (Whether Apple Watch will suffer a similar discrepancy between the promise and the reality will be key to its long-term success.)

Ultimately, one could argue that the value in hugely ambitious projects such as Glass or HoloLens is less about rolling out functioning devices right now, but more in burnishing these companies’ reputations for innovation, for having the ambition and vision to try to invent the future.

But I’d suggest these firms pay a high reputational cost by overpromising – by depicting these “moonshots” as imminent when they are actually far from ready for release, they waste a good deal of our time and attention, and ultimately, they undermine that valuable sense of wonder that great, real technology can inspire.