You can still buy regular lego blocks, windows, trees etc. exactly how they were in the past, it's just that they don't market those as heavily as they're less exciting. The pictures posted are from one of lego's 'sub-brands' like 'Technic' aimed at slightly older boys or their 'Bionic' creatures or the 'Belville' brand aimed at girls.
It is quite clever, although tacky, how they've teamed up with various other people to make up-to-date kits like the Star Wars and Harry Potter lego. They have to change their products to keep up with the stiff competition in the form of video games, tv, electronic toys etc. If they just produced regular old bricks they wouldn't survive, and have had to have tapped into popular culture and other popular themes like 'fighting robots'.
I actually still have a big box of old-style Lego and there are some pretty cool pieces which aren't all flashy and curvy and based on films, like the mini lego CCTV cameras, solid plastic bank notes, clumps of flowers, flags and flames! Even those extras which allow you to add fun little details to your block constructions through the well designed pieces aren't enough to grip the market these days, it would seem.