Sorry deepu priyanka, you find them atractive, and many people find them annoying. It makes reading really hard. Take into account that many people here are not English speakers.
Plus it´s an universal sign for screamming on the web. Language is universal so that we understand it the same way. I can make my own version of it, but I don´t see the sense of it. I can tell you that for me Zs are As or something, but I cannot wait it to be accepted.
Plus Caps in the beginning of a sentence means something and makes writing understandable.
Don´t want to bash, want to make you see why this is annoying.