HTML is a huge pain in the ass to write:
* It requires balancing tags
* It's verbose
* It is crudded up with syntax (</-="") and keywords
* It consistently runs right off the 80 column right margin
* It's an enormous pain to extend
* It's slow to read; for instance, try picking the plural version of a constantly-used class name out of tag soup
Haml isn't a shortcut to writing HTML. On the contrary, to use it well, you have to know HTML well. What Haml does is to solve the problems that make HTML a pain to use to express user interface in.