Yes. You are totally correct. Allies are very disappointing in this game so far. I would love to see more options in alliances and it all doesn't need to be based on moral preferences only. I hate it when I am play pragmatic and another faction is good and even though I have been really good to them, I am still taking a penalty that could undermine our relationship?
Well I digress. I like what you tossed out there. More alliance options. So far we go
Open borders ----> Non-aggression-----> Treaties -------------> Alliance
But even in Alliance, there is no guarantee that they will actually help you nor are you bound to help them. Even the total war series prompts you that your ally calls for aid and to refuse damages your rep in the world.
I would change the diplomatic relationships to the following:
Establish Formal Relationship, this would unlock a few basic options ---> Open Borders, Trade rights, Collaborative Exploration, Non-Aggressive Pact
Once your relationship with a faction improves to good relations and you unlock the basic treaties you can then enter into
Multinational Relationships, this opens up a few additional options---> Mutual Defensive Pact, Preferred Trade Partner, Collaborative Scientific Research
Additional Research and good standing allows:
Transnational Diplomacy which unlocks ----> Military Alliance, Trade Pacts
Now a few things to note. 1) open borders should be just a privilege not a diplomatic move. In some games crossing into another's territory is an act of war. Why is there not even an alert that your going into someone else space? 2) An increasing trade status. You can trade with anyone even if they hate you. The only limit is if your at war. Negotiation of trade rights is normally a big deal. I added in advanced versions opening the door to maybe some additional economic options. But I won't expand here since this isn't the discussion for it. 3) Alliances would open a panel that could include more than 2 nations. Now being in an Alliance, as compared to a Mutual Defense pact is that MDP is just an agreement if someone attack either you or them you help out. You can still negotiate a separate peace. But Alliances agree to see it through to the end. If you all sue for peace it applies to all nations evolved. It also requires all parties to join in the fight should one attack another nation not involved in the alliance.