Ability to designate empire Capital via System Development tab

I like that you can upgrade the level of a system via the System Development tab. However it would be good if there was an option unlocked after the 'nation' level was the ability to upgrade a single planet to be your 'capital' to add a feeling of uniqueness to your most developed system.

I find that late game every system under my control feels the same, you just end up building every system improvement available. This idea will at least set one planet apart from the rest of them.

You could have special attributes attached to the capital, for instance you could make it so if the capital system was captured morale of the other planets would take a huge hit. This in turn would create a new strategy of trying to conquer your enemies capital to inflict massive morale damage across their systems.