You are talking about the exteme parts here all the rest have a minimum of 5
That means they are programmed to go to war.
From what I gather these attributes work interactively - so they may be 'programmed to go to war' based on their warmonger attribute, but whether or not they actually go to war, and who they go to war with, will be determined by other attributes like Loyalty which dictate their reaction to diplomatic overtures, who their friends are, who's been denounced and so forth.
Which in principle is probably good design; in Civ games war is the outcome of failed diplomacy and the only situation in which it much matters whether a civ likes you or not (except in past versions of diplo victory). So surely you want a system where leaders are likely to go to war if you don't do enough to dissuade them, as opposed to civs you can happily ignore throughout the game in the sure knowledge they won't actually do anything. For example, in most games I've played Gandhi tends to hate me, but he will almost never go to war even if he's been hostile for most of the game, so I tend not to much care if he dislikes me.
And isn't 5 an average sort of value on the scale the game uses, rather than a value which suggests they're all likely to be warmongers?
The reason I think that this approach doesn't work the way it's supposed to in Civ V is that the diplomacy system isn't designed well enough - most of the things that affect relationships (including the really big one, settling near their territory/settling territory they want) are at least partially outside the player's control. So if you have a system that relies on the player controlling their diplomatic relations in order to avoid war, but which simultaneously gives that player very few options to control those same relations, you're going to get more declarations of war than you ought to.
I really think the game would be too easy if there were too many loyal civs. Also, it would not be very historically accurate. IMO history shows us that nations generally only support other nations when it's also in their best interest. No one is doing it out of the goodness of their heart due just to "loyalty".
Realism has never featured in Civ diplomacy, and it's hardly a notable feature of Civ V generally. The reason you need things like loyalty in the game is because decisions about whether X is a good ally from the point of view of your best interests demands a far higher ability to understand your own interests and how the odds of a good outcome will be affected by allying with Y or declaring war on Z than checking a statistic, an ability which is far beyond the capability of even a good AI. It's very far beyond the capability of a Civ V AI that struggles to recognise that it's in its best interest to complete the spaceship if it's going for a science victory.
To be honest, it's already a large part of the reason Civ V diplomacy is flawed that the AI is trying to pull off more complex tasks than in previous games and can't handle that, let alone any more added detail.
I think the intent of the diplo system in this game, when compared to previous versions, is to make the AI more ruthless and Machiavellian.
Not necessarily more 'ruthless' - what it does seem to be trying to do is to make the diplomacy system more dynamic, apparently as a response to criticism that Civ IV was too predictable. You can't always rely on the same behaviour having the same results, or on relations remaining static because you traded favourably 3,000 years ago. This is what the denouncement/declaration system seems to represent - you can be getting on brilliantly with another civ, right up until someone else denounces you and they think "hang on, is this relationship really a wise idea after all? Can he actually be trusted?" The fact that declarations/denoucements only last a limited time likewise allows relationships to change over time much more than they would in Civ IV.
Once again, this is a great innovation in principle, and denouncements/declarations are a clever tool to influence relationships between two rivals indirectly in a way that was less feasible in the older games. But the trouble, again, is that the AI can't handle it. Civ IV asked its AI to perform a much simpler task - basically, to count its plus and minus modifiers, all of which accumulated over time and didn't really change over the course of the game except for the odd change of religion or civics, and make decisions entirely on that basis. By its nature that's a predictable system, but it is at least one a simple AI can understand and execute. By contrast the denoucement etc. system is one that relies on the AI knowing who its rivals are, what the likely outcome in terms of interactions between those civs will be, what the likely outcome will be in terms of those civs' relations with it, etc. etc. All stemming from just one decision. Being unable to handle this kind of decision-making, the AI instead seems to end up choosing who it denounces at any given time largely at random.
Like they are always trying to win, not just to make the game more fun or easier for the human.
Again, a problem resulting from overcomplexity. The game *should* be trying to win, I don't really understand people attempting to use this supposed feature as a criticism. But Civ is a complex game that demands long-term planning and an understanding of several different possible routes to victory. The AI doesn't really try to win, and isn't capable of doing so, except in the simplest sense of trying to have a higher score than its rivals. It will even build two spaceship parts and then stop building any more when it's in a position where it could win. It's all stuff that is a great improvement over previous Civ titles in principle, but simply doesn't work in practice.