Let me offer you a different analogy.
4e's PH, DMG and MM are like big tubs of different legos. You can build all kinds of cool stuff with them; however, if you buy (f'rexample) Martial Power, it has purple legos in it. Wow! There weren't any purple legos in the original books. Then if you buy PH2, you find that it has some shiny, reflective legos; PH3 has some legos that light up from within; etc. Each set of legos offers new ways to build stuff, but none of them make the original simple red and white and blue bricks obsolete or less useful; they just continue to add options.
I suspect that the Essentials line will add orange and black legos, as well as some that have simple moving parts so that you can build rotating devices like windmills. Also, maybe some curved ones, or something neat like the old moon surface lego terrain or whatever they called it.
But you know what? You can still build lots of things that are plenty cool with just the different sized bricks in white and red.
Lego designers however found that the original red, white, and blue blocks were too cool for school...and since legos in schools is a big deal, they have been "updated" and no longer resemble anything cool at all.