Monster Cable did go after Monster.com as well as Disney/Pixar for Monsters, Inc. so they are going after the big boys. They obtained undisclosed settlements in both cases. At Monster.com, there is a link to Monster Cable at the bottom of their main page which was placed there as part of the settlement.
Most people don't realize that Monster Park in San Francisco is named for Monster Cable and not Monster.com. Monster Cable is a privately held entity so it is unclear how much of their revenue comes from cable and electronic products and how much comes from extorting licensing fees for the use of the word "monster".
Anyway, if you think there actions are wrong, I encourage people not to buy their products. I am all for trademark protection. If you earn your good name, you are entitled to protect it and not have people profit from your well-earned reputation. But not when your name is a common English noun. I wonder when they will pursue an action against Head Skis.