Probably the most accurate answer to your question is: Because so many people don't know they are not required. (I certainly was in that category until about 5

Probably the most accurate answer to your question is: Because so many people don't know they are not required. (I certainly was in that category until about 5 minutes ago) But even now knowing that info... I will continue to use them. Yes, it adds another level of indenting... but personally I prefer that. Text that is without a left margin tends to be a little harder to read. I also like to have a visual grouping of the elements. I think I would disagree that it "makes it more complicated" to have those tags.