All-in-ones are meant to be seen. From the Twentieth Anniversary Mac to whatever Dell's selling these days, all-in-one computers are built to embrace their top-of-the-desk status, beckoning users with sleek curves and handsome enclosures.

Nowhere is this more true than with the iMac. From the early days of Bondi Blue to the newest aluminum-and-glass marvel, the iMac has always represented Apple's unabashed pursuit of physical perfection. In a sense, it could be the ultimate representation of form over function; every sacrifice has been made for the sake of design, every decision has been made for aesthetics.

But it's hard to argue with the results.

When the iMac hit the scene in 1998, it was a revelation. Joining a computing landscape filled with unimaginative, shapeless towers attached to clunky monitors with unsightly cables, the iMac dramatically changed the way we saw PCs. Clearly developed for home use — I don't think Steve Jobs expected many businesses to buy blue computers — the semi-translucent sensation was nothing less than a warning shot: Apple was going to take risks.

But it wasn't just the shape, color and mouse that were risky. To keep things nice and symmetrical on the front of the machine, Apple ditched the floppy drive, a staple of late-'90s computers. There was obvious backlash — louder for sure, but not unlike the one seen when this year's model ditched the optical drive — and Apple had to expect it when the decision was made.

But design ruled. Either Jobs or Jony Ive (probably both) felt that the inclusion of a floppy drive just wasn't worth upsetting the impact it had on users when they first laid their eyes on the iMac. 

After all, that's really what Apple's in the business of: first impressions. Ive wants you to fall in love at first sight. So, these sacrifices matter.

That's why the new iMac traded its optical drive for a 5mm edge — a razor-thin slice that you probably won't even notice while using it.

Remember the iMac G4? Perhaps the most visually striking computer ever made, Apple desperately needed to follow up the by-then-outdated G3 with an absolute winner. It would have been easy to play it safe with a derivative design, but Apple threw another curveball, unveiling a jaw-dropping enclosure that abandoned any traces of convention the G3 may have had.

The form certainly came first — Jobs famously told Ive he wanted it to look like a sunflower — but not at the expense of function. With the G4, Apple nailed every note, from the "floating" display that swiveled and pivoted on a chrome arm, to its dome-shaped, colorless base that packed serious processing power.

With the iMac G5, the "creators of iPod" again shifted gears, basically crafting a display that deftly hides a computer. It seemed so obvious, so simple, yet the iMac remains inimitable, despite Apple having never changed it again; the past several revisions have all been variations on the G5 theme, culminating in the gorgeous slab we see before us. It may not be not as revolutionary as the G3 or as astonishing as the G4, but the iMac is nothing less than the result of pure Apple refinement.

The iMac is in many ways Apple's perfect machine, a brilliant triumph of form that just so happens to be pretty darn functional.

Find Michael Simon on Twitter or App.net @morlium.