The Lego was patented 50 years ago. Patent terms generally range from 17-20 years (from issue or filing date). So Lego's original patent expired long ago.
Patents cover functional inventions.
Also mentioned is an earlier Boing-Boing story in which functional aspects of the Lego brick design were denied trademark protection.
Copyright (not mentioned in the article) and trademark do not cover functional design, but literal expression (copyright) and trade dress (trademark). So, a rectangular brick functionally compatible with Lego bricks made by Acme, Inc., and branded appropriately, doesn't infringe Lego's trademark for its functional aspects. Even if these mean that the visual design of the brick is highly similar to a Lego brick (as it would have to be).
Similar findings have been made in copyright law, particularly Sega v. Accolade, in which case a literal reference as part of the activation code of a compatible game was found to be functional, and hence, not a copyright infringement.
Lego had a patent on the design of the bricks 50 years ago - but failed to get a trademark on the shape of the bricks.
Apple got a design patent on the general shape of the iPad. Design patents are a convenient way to get around the fact that trademarks offer much less protection than patents and are generally assessed rather more sensibly.
My point is: even if they'd secured a trademark on the shape of the bricks, if that trademark covered functional aspects of that shape, the protections would not apply. Lego could attempt to enforce them, but a competent defence and court would reject them.
I'm sure most or all HN users would agree that the current patent system is broken. However, as is mentioned in the article and as semanticist pointed out, Lego was able to get a patent on an "obvious" idea, and so was Apple. In other words, a similar argument did apply.
Obvious in retrospect. I had a friend who was a world expert in pen and touch interfaces and he had tablet computers from all over the place. None of them ever looked remotely like the iPad. They were all funky mishmashes that looked like they had been designed by committee whose main pool of ideas was based on hinges, swivels, styluses, and hideable keyboards. They were horrendous, but it wasn't obvious why until after I saw the iPad.
You can't patent this meta-idea of a "clean design". The idea of portable rectangular displays with pen and touch input since the old sci fi shows. Apple simply didn't invent this.
From what I read, the mere aggregation of existing things is not of itself considered patentable. It doesn't make sense to me that anyone would consider the removal of knobs or buttons to be worthy of patent protection. (But then again, almost nothing about the patent system makes sense to me.)
Trademarks are to protect brand names and brand identities. Patents are to protect inventions and technical and design concepts.
Lego could, and did, get patents for the blocks. That's the entire point of the Boingboing article - the patent was granted and has since expired.