I disagree as well. Mordor does not need to be buffed in any way. They are already contending for the strongest late game faction and arguably the strongest faction overall. They have ample options to deal with their enemies. They have the best siege in the game, a ton of heroes that scale in power with Sauron, their basic units are free, they have a spell that can make the recruitment time of orcs near instant allowing the replacement of lost orc hordes, Sauron's Past Ages Power turns him into a combat-ready hero, with his blade of destiny making him arguably into another hero killer. He can also become a mass slayer with light siege attributes by becoming lord of the Werewolves. He can become Annatar, lord of gifts to deceive your opponents and punish defensive play and he can turn into a vampire, leeching health from troops in the long run and giving it to himself. There is so much versatility in this guy, it's crazy. In the right hands, he can almost become a one man army. He can't even die normally, you purchase him only once. Does he really need anymore?
Furthermore, remember that any buff you give to Sauron also (partially) transitions to the Nazgûl and the Mouth of Sauron, buffing all of them as well, since they are tied to each other.
The combination of army supporter and mass slayer is rare and probably the best in the game. I don't remember who, but someone said on the forums: Surrounds him by orcs, and he is invincible. The only reliable way to beat Sauron is with a hero killer, but what are hero killers weak to? Exactly, regular troops. With them, you can make Sauron temporarily have no weaknesses. Only advantages.
Finally, Mordor doesn't really have any apparent weakness like Lothlorien or Isengard, in my opinion. They can keep up with Rohan early game, which is arguably the best at the moment due to peasants and their late game is arguably the strongest due to their ability to endure via numbers and their large amount of heroes. I think Mordor will stay the best faction in the game, if not, one of the best until perhaps Misty Mountains are released, which share a similar nature. Massive and unending hordes.
Kind regards.