If they want to make a DRM'd DVD that can only play in a special DVD player that is their right to do so. You do not have the right to force these companies to make the product that you want. You do have a right not to buy it.
Yes, producers have a right to produce copy protected products, and I have a right not to buy them. However, I cannot know if there is copy protection on the product or not until I have bought it, opened it, and examined the media and/or the license that came with it.

Since I can't return the product in the case that it turns out to be copy protected, currently, I don't buy any form of digital media because I have no idea which ones will restrict my use and which ones don't. If there were mandatory labeling, I would buy more.

Requiring labeling for copy protection accomplishes the same goal as any other labeling -- it allows the consumer to make a more informed and confident decision. Informed and confident consumers are a pillar of free markets and healthy economies.