Right the blank would not override the list, it would just be there in cases where there is no default value. The list is in alphabetical order, so if there is no default value, it will give you the territory that is alphabetically first in the list, which is usually not the one you need to select. In those cases, the blank gives you a clean list to start from.
If there is a territory selected in memory, it should still be selected and highlighted in the list. For example, you attack, then advance troops to the newly acquired territory. That territory is held in memory and is provided as the selected and highlighted option in the list. I am not sure what logic they are using right now, but it does seem to be pretty comprehensive. This would not change that logic, it would just start you off with a blank when nothing is held in memory.
For example, the logic only puts territories in the list that are able to take action. Lets say that you are attacking, and you are clicking away, until your territory is down to 1 troop, but you accidentally click attack again without realizing your territory dropped down to 1. The list has already automatically switched to select the first option in the attack from list and the first option in the target list and now you have accidentally attacked because you clicked without paying close enough attention.
Does it happen all the time? no. Does it ever happen? yes. I know that one answer is "pay closer attention" but sometimes you are trying to get your actions in as fast as you can. I know this is not a mission critical enhancement, I just think it could make things a little cleaner. I'll hop off the soap box now, sorry for the long post.
