Well, remember that Sauron in Bfme2 and Rotwk did cost an insane amount of money to make (like 10000 resources if I remember correctly) as well as actually obtaining the ring. Because of this cost, his insane Health, Armor, and Damage is justified. In Edain, Sauron only costs 1000, and can't die like a normal hero, so you never have to pay that 1000 again to get him back. So I don't agree that he should be as strong stat wise as he was in the other games.
What makes Sauron different from Bfme2 and Rotwk is his abilities, which were really lacking in those games. He has the largest ability roster of any Ring hero in Edain, and his abilities make him very strong at taking on larger armies.
Remember that Citadel Guards cost 1400 per group, and are Gondor's strongest infantry. Since they only take off 1/4 of his health before they die, that means Sauron can kill 4 groups in a row before dieing, and 4 groups of Citadel Guards cost 5600, which is a lot. And that's assuming he uses no abilities at all, because if he does, with just the Heal he has alone he will be able to kill 6 groups, and with all the others I'd assume a lot more than that.
Sauron should be the best ring hero in the game, for obvious reasons. And right now, I think he is. The only one that is a close contender is Saruman, whose Knockback on normal attacks and Insanely powerful abilities bring him close to, if not equal with the Strength of Sauron. Saurons still needs to be able to be countered by something, and right now I think he is in a good spot. I wouldn't mind seeing maybe a very small increase to Sauron's base stats, but nothing more than very small.