It’s not enough to have the best idea. You have to execute it correctly as well. And sometimes that means waiting until the technology catches up.

I present Exhibit A for your consideration:

The Asus PadFone is a “system”, if you will, for having your phone act as your main computing device. You can plug it into an empty tablet computer case to upsize your screen, and a laptop keyboard to turn it into a traditional PC workstation. You can read the full review at The Verge, and I recommend it as a terrific overview of an interesting new computing experience.

The Verge, and similar publications, share a common flaw of being a tad too forgiving of flawed products. I mentally handicap such publications when I consider the extent to which I should heed their buying advice.

I mean, they recommend Android, with a straight face. We’ve covered why that’s a mistake, I believe.

Actually, a link to last week’s article is totally appropriate here. No surprise: the PadFone is an interesting idea that blows it on the execution.

But there’s a mighty big asterisk in that last paragraph: we have an interesting idea! Let’s give it a closer look.

The Phone is the Centre

I think it’s becoming pretty clear that, as computing power continues to shrink, fewer of us will need a full-size PC to conduct our mainstream computing tasks. With an iPhone or an iPad, you can browse the web, work with email, hang out on Twitter, track your diet, watch video, buy music, draw cat pictures, write a blog post, and much, much more. As my mom’s MacBook is starting to flake out, I’m socializing her on the merits of upgrading to an iPad.

It’s like what Steve said: traditional PCs are trucks, and most people only need cars.

For these putative car users, if all the processing power they need can sit in a shiny pocket-sized device, then why can’t they just have a pocket-sized device?

Because of the screen, and because of the way you get text into it, that’s why. This is the insight that’s driving the PadFone. We’re past the point where we’re worried whether portable devices like the iPhone (and — sigh — Android phones too, I guess) have the oomph to accomplish the jobs we hire it for. Now, we’re trying to figure out how those devices can be as comfortable to use as a PC.

I think of there being three major modes of work with computers:

1. On a mobile device, on the spot doing quick triage (dealing with email, reading tweets, answering the phone).
2. On a tablet device, consuming content in a relaxed environment (reading and replying to email, reading a book or long article, playing a game). In this mode you can also be working in a mobile environment (think of tablet applications like medical imaging, forms and surveys, and reference materials).
3. On a traditional PC laptop, creating content (writing a book or article, working with images or film, building web sites, programming and the like).

I think the PadFone has the right idea: we need an interface to allow us to use just one computer with all of these modes. Consider the absolute win for ease-of-use: you don’t need to sync stuff between machines anymore, and you have your entire digital life with you, always (or, most likely, in the cloud).

But the PadFone fails because that interface is a crude amalgam of old technologies: a motley collection of snap-on toys that feels kludgy and whose workings are twitchy at best.

Let’s play one of my favourite games: What would Apple do? What if Apple were convinced that computing was moving in this direction?

I don’t think they would plug an iPhone into some kind of empty iPad, which would plug into a display-less MacBook keyboard. Apple doesn’t like plugs. In their perfect world, everything would be wireless: your iPhone would stay in your pocket. But they could offer a variety of displays for it. Imagine a 10-inch plate of glass that could be paired to your phone, and provide an iPad-style interface from the phone.

In fact, Apple already has the pieces in place to support this idea. With AirPlay, an iPhone can send its screen to an AppleTV. And with Universal iOS applications, a single application bundle can run on both an iPhone and iPad, providing the appropriate interface for each.

It seems conceivable that, as the Mac and iOS continue to merge, it’ll be possible one day to build a kind of Universal app that includes iPhone, iPad and Mac-style (perhaps not Mac OS as we know it today, but more accurately, a large-screen window environment) versions. Then, your iPhone can AirPlay that app to an even larger display, such as a Cinema Display (or hey, let’s think big! My wall!), including a track surface and keyboard.

Now, that feels like the future. Call it ubiquitous computing: a single device in your pocket that can drive any empty computing receptacle that happens to be sitting around (as long as it has an Apple logo on it, of course: this may be the future, but not everything will change).

Of course, my guesswork could be completely wrong. But it seems plausible; if you believe in the direction the Asus PadFone is going, it’s a question of execution. Asus got it all wrong, but I think Apple could do it right, and this is what I think it would look like.

The funny thing is that, given their current technologies, you could say that Apple is lining up to do just this.