Doing it from the add dialogs instead would prevent the call to these dialogs outside of a breakpointWindow which would be necessary for hotkeys binding.
The old one wasn't very optimal because not only the user would likely want to enter an address instead of a range, but it also made entering just one address confusing (you had to have the same value on both start and end). Also, you should only chose one option between read, write or both, there is no point to not have any.
This is why I made more clear how to add an address and it is the default option using radio buttons and I also made the action flags and the flags to be radio buttons.