I see it in my head as shouting too......having used the net for some 12 years now I really do take it to be just the same as conversation in real life.....always makes me laugh when I come across people who say its silly and you cant make friends with people online....then I let them know about the people I know in America who I went and stayed with and some of whom have come over here etc.....its all very real, just some people havnt woken up to that fact yet.....
thing is though, some people shout at you in real life......still dont like it, but what can ya do....
I just don't read it at all. Someone's clearly gone out of their way to make the text less readable by breaking the flow of the sentence - it's so much easier to read correctly formatted text, so I refuse to read it!
Depending on who has written the text, and the context in which it is being read, I take capital letters, to mean either someone's shouting, someone's emphasising something, or laziness in typing. But, unless the person has written something really stupid or frivolous, I tend to simply ignore it.