I have seen a few similar requests to this one, but they contained some other items in the request, so I wanted to make this one (hopefully it can be included in v12).
In v11 of Forms we received the ability to make the user task comments field required or be able to hide it using Field Rules, which was a great addition. In most cases though, a comment needs to be required based on which Action button is clicked.
While you can create fields to handle the approval and a comment, there are benefits to using the built-in functionality of Action Buttons and the User Task Comment field that adding your own fields are not able to take advantage of.
For example, when using Action Buttons, the button clicked is recorded and shown in the Action History as well as various reports. Action Buttons are also used for the Direct Approval feature. The built-in User Task Comment field is also available in the Action History.
I try use the built-in features of the software whenever possible and adding this feature would help accomplish that.