That's an excellent question, Webeida! And let me answer it simply: We would have the same boring sidebars on every single page and post of our website. But, thanks to the goodfellas behind Dynamic Widgets, that problem is a thing of the past.
You can make any website look great, look dynamic, look wonderful. I would dare say that, without dynamic widgets, WordPress would be where black and white TV is today: lifeless, soulless, without dept, without colour, without warmth.
You can see how I have used Dynamic Widgets to its fullest on my website for cycling tours, bike hire. It's based in the West of Ireland. You should go there some day!