I’ve made similar analogies to the development of automobiles that Gruber is making in his iPad thoughts post. But in my case its a general analogy about things getting easier to use and more reliable, with less of a reliance on mechanics to make purchasing decisions. Gruber’s missing the main difference between autos and computers: software. What he’s describing is a world where there is no customized software. And by “customized” I mean software like Nisus, or Acorn, or Pixelmator. Any complex software not made by Apple.

The analogy to cars fails because cars are hardware. They can’t be a truck when you need hauling, a subcompact when you need to park, an SUV when it’s time to haul the kids around, and a Cessna when you need to get to Dayton tonight. Computers can. A computer can let you play a simple game in one minute and save your business in the next—if the software is available.¹ In today’s world, the software is always available, if you’re willing to pay the price. In a world of app stores, you have to live in the underground world of unlocked computers, furtively applying upgrades in the dark.

Automobiles never went through a transition where Ford made vehicles we could change from compact to pickup and then they decided to take away that advantage. This is a feature of software. The advantage of software is that we don’t have to rely on Apple/Ford to approve new uses for that thing we bought. Everyone benefits when programmers can program.

The analogy would be an inability to add a bike rack or a trailer hitch or a child seat to your Taurus without going through the Ford PonyStore. The only way to replace your tires is to send it back to the dealership. Don’t even think about getting a better radio. That duplicates existing functionality and will not be approved!

You bet the carmakers would love to require everything new go through their own dealers. And that world would suck.

Most people want something custom for their computers whether it’s spider solitaire, a geneology manager, or a writer-centric word processor. And there will undoubtedly be more complex software for the iPad than there is for the iPhone. But it won’t be as good as it could be. The three-week to three-month approval time drastically depresses the feedback loop for improving software.

While I would never buy an iPod Touch, I do enjoy having one. But I enjoy it because it’s an appendage to my real computer and it makes my real computer more useful. It’s a remote control for my music; it’s a way of synchronizing notes; and its a way of keeping my browser bookmarks, address book, passwords, and so on, with me at all times. But it’s useless without that real computer that other people can program without having to get approval from Apple. Sure, the iPod Touch plays nice games. But I’m not going to carry it with me at all times because it plays nice games.

The iPad is not small enough to carry with me at all times; it will have to be more like a real computer.