Totally agree. They added a campaign mode to the arcade game so it should be better balanced. Easy is still very difficult. I've yet to finish even a short easy campaign. I also find the interface and systems confusing since they are not explained well. If I unlock a weapon is it available for future games or just the current game? And what are the blue items that drop from enemies? Are those the credits? I really like the core game but it's in need of balance and a manual.
The furthest I've got is about 7 hexes into an easy campaign. It's hard as fuck but I like that!! Here is what I have gauged so far: (if I'm wrong then someone please correct me)
The blue chips are indeed credits and you can use these for upgrades, lives or weapons previously unlocked.
For upgrades in-between mission while looking at the hex map press r1 and it will bring up the upgrade menu. You can freely allocate any existing points as you wish (so could remove everything bar front Shields and put all your existing points into that, although I wouldn't recommend it lol). You can then use your credits to buy additional upgrade points with an increasing cost per point - so 1st point is 500, second is 750 third is 1000. As far as I know upon starting a new campaign, all upgrades reset.
For lives, on the hex map look to your left slightly and you will see an option to buy a life if you hold down square. Again, lives increase in cost as you buy them like the upgrade points.
For weapons you need to visit a supply point on your hex map. When you do I believe it generates a random choice of weapons from a stock starter plus any unlocked weapons you may have got from previous campaigns. Weapons available to buy will change every campaign and purchased and equipped weapons will not carry over to a new campaign.
Hope this helps. My strategy so far on my latest and most successful campaign (half way through so far), was to juggle between buying extra lifes and tank upgrades. At a supply point I sold one weapon for a mark 4 upgrade of the same one. Patience is key. Try to avoid rushing in and definitely don't be afraid to run away to cover (I've found they follow you in small numbers enabling you to pick them off between cover)
Edit: just another thought but it took me a while to work out some of the missions. The ones where you have to hack an enemy Base before they hack yours, I found just head straight for their Base and hang in there while completing the hack. When I tried to defend mine 1st I got slaughtered. Yes the payout won't be as great as you didn't destroy enemies but you complete the mission