I mean I understand both sides of the argument, but it seems like physical goods manufacturers are doing fine without enforcing restrictions on how their goods are used (I am free to buy an off-the-shelf power tool and then rent it out without paying extra to the manufacturer), so why are we giving this exception to content producers?

In my opinion the law should be changed that content you pay for can be used as you wish except copying (otherwise you'd just copy it and resell). It'll drive up the prices of the "source" content, but the market will quickly fill the gap by offering affordable access to broadcasted versions of such content.