When you work with computers, especially if you work with computer graphics, you are dealing with pixels. Digital computers (which is what almost all of the computers nowaday are) need to digitize data. Read Nicholas Negroponte's Being Digital. Digital computers digitize all the analog signals around us - pictures, sounds, ideas, etc. Geeks who love to use computers to manipulate bits are using a powerful tool to create and modify things in a virtual world that models the real analog world.
Digital building blocks allow us to assemble many different things quickly and with great flexibility. However, not being about to touch your creation still leaves you with a kind of empty "feeling" (pun intended). Imagine if you could not only see Lara Croft's 34D bust, but (gasp!) touch it as well.
What does this have to do with Legos? Are Lego's usually wholesome? Why am I bringing up Lara Croft's bust? No reason except to put in that last link, in case anyone missed it the other times.
Anyway, I digress.
The reason why we love Legos is because they are physical digital building blocks that allows us to build practically anything we want. Heck, Legos even have jaggies! Furthermore, depending on whether you go for regular Legos or possibly the jumbo-sized duplos for kids, you can control the resolution of your physical digital creation. How cool! Lego has even created anti-aliasing for their jagged blocks with those slanty blocks.
Let's face it, most of the time, we like to build or see people build those large zillion-piece lego models like this guy does. And what he does is create three-dimensional Lego-voxelized representation of things. We don't like the Lego sets with the prebuilt themes as much (my opinion). Lego's even got a brick-o-lizer that helps you take a flat 2D image and create a mosaic of the picture with instructions to build it from Lego blocks. Using Legos is one of the coolest ways to digitize things. And if you are particularly clever, you may even use error-diffusion dithering to render the image more "realistically"
This is why geeks like Legos, I believe. The colors help. The relative wholesomeness gives it more parental support. That it involves more imagination makes it a better toy and more fun, especially for the engineers among us.
How many of you can't wait till we get nano-Legos?
Lego Star Wars Trilogy
Lego my Eggo!