Why aren't radishes more like green beans?

I usually pick a couple wild radishes every winter. They get really woody and hard to eat when they are large, but when small they at least taste like normal radishes.

Rat's Tail Radishes are a variety of radish which is grown for their seed pods instead of roots. Buying them convinced me to try and eat some pods of a wild radish plant. I no longer understand why ancient people decided it was the root they wanted to breed radishes for.

The pods and roots taste fairly similar. Both have the stereotypical radish taste. However with the wild radish the total amount of food you can get off of a plant from the root is tiny. I couldn't imagine it being easy to make it a large part of your diet. On the other hand a single plant can produce dozens of pods which are quite easy to gather.

One article I found suggested that the answer to my confusion is that the podded radishes were common before the Civil War. They only became uncommon recently.