Yes, I know Itachi’s intentions, but it would not make sense to have him succeed without us seeing some sort of development from the Kages, Sasuke, or the Uchiha clan as a whole.
1. If Itachi ends edo tensei without the Kages fighting back, and actually make Madara work for it, they would look like absolute crap. The title Kage would lose its prestige and honor, and I can’t see how Naruto achieving it would be an accomplishment at all. I don’t care how powerful Madara is, he is still one guy facing off against the shinobi leaders.
2. Sasuke got the true power of the “Uchiha”, yet we don’t know anything about the EMS. Madara is not using his eyes for a reason, so we can see the new techs for the first time along side Sasuke.
3. Madara has no reason to lie, plus he basically started it all, so it would be dumb to not use him to demystify the Uchiha clan and clue us in on the Uchiha tablet. He is also one of the only who can show us everything Hashirama was capable off in his prime.
All of this won't occur if Itachi succeeds.