Madame Danglars is an enterprising, independent woman. She's landed herself a rich husband. Using certain "government connections," she's found a way to become independently wealthy, too. All positive things, right? Certainly more interesting than anything the demure Valentine de Villefort ever did.
The thing is, all of her gumption and chutzpah only gets her into trouble. She mothers an illegitimate son and is subsequently wracked with guilt when he turns out to be alive decades later. Her marriage is a mess. Her daughter hates her. She's just another example of how deviation from the loyal, motherly role doesn't pay off in this novel. Heck, not even Mercédès gets a free pass.