Thank you for your feedback.
It is an intended design, so you have to fight for those points, as 'Coast Defense' and 'Valley' both have their respective perks of owning them. While 'Coast Defense' is not available for immediate attack.
So once you haven't got 'Valley', you better focus on having 'Coast Defense' as a means to attack 'Valley'.
Strategic imbalance to tip the scales during the battle, in attempt to introduce some variation depending on the captured objectives.