Quite often, I will have a narrow legend on the side next to my map because it is a standort layout for my company. If I have long labels and long descriptions, and want to display both, it shrinks the font size considerably.
Usually, I make dummy layers for the descriptions, and add them separately to the legend. That can get quite tedious though, and it would be much easier to have the option that the descriptions starts below the label.
Here is an example how the dummy looks like:

Here is how it works otherwise:

The dummy is a lot of work, especially if you don't have single symbol but several unique values, since you need to separate them all and create a dummy for them all in order to show them in the right order.