I'm surprised also, but maybe for slightly different reasons.
I once read an article discussing why most teddy bears on the market have infantile proportions (big heads, short limbs). It turns out that these proportions are not especially favored by children, who like realistically proportioned bear dolls just as well. Those proportions are meant to appeal to the parents, who are the ones making the buying decisions in that market.
The principle is extendable to other markets: Appeal to the actual punters, not necessarily to the end users.
In this case, the law firm's ad looks like it appeals to the improvident chicks who became immortalized as cocksucking bimbos. The casual obscenity, informal tone, and promise of simultaneous revenge and cash would exactly appeal to these types.
However, these women rarely have the money to fund this sort of thing. They're generally going to Daddy for the cash, and I'd think fathers would find a different approach more appealing. What Daddy wants isn't brashness and outrage, but quiet competence and the promise that this nonsense can be made to go away with a discreet application of money and leverage. A website that appealed to Daddy would look and read nothing like this one.
So what's happening? Are these lawyers really bad at marketing themselves? Do Daddy's girls exert more influence over the choice of a law firm than infants do over their toys? I'm not sure, but they've made an interesting choice here.