War level suggestion alternative
I thought of yet another idea to maybe make players move from their lower war levels and reward them more than just gold coins, is to make them earn and unlock more advanced weapons they can use in wars as they become more experienced in war. This means there would be a war level clearance for each weapon in the game. This is just an example of how this would work.
War levels 0-2 ( Can only use basic defensive and basic offensive weapons in these levels, this would indeed help new players learn about the basic weapons in this game as well as learn about the basic war side of the game much more quickly without the worry of other players attacking them)
War levels 3-8 ( Unlocks most defensive weapons, including most defensive aircraft, most offensive weapons, as well as some aircraft, naval weapons and strategic weapons for you to use from these levels. This is where you will be more experienced to use these more advanced weapons in wars against other players too)
War levels 9+ ( All types of weapons in the game are unlocked, including all strategic weapons for you to use from this level, however weapons that are unlocked at this level cannot be used against players of lower war levels)
A player at war level 9+ for example can use weapons against a lower war level player that have the same war level clearance as that player.
Also if you are in possession of some strategic weapons like nuclear weapons in war levels 3-8 for example and if that weapon can only be used in war levels 9+, it means you are forbidden to use that weapon in wars as you are not cleared to use them yet.
This is my alternative to Supersoldier's idea, Aries, i'm not saying it's any better though, but I believe this will make a lot of players go up to these levels if they want to access and use these better weapons for war. I for one, would do this myself if I wanted these better weapons.