Even though Sasuke attacked Madara so recklessly, he went in with a plan.
He clearly was aiming for Hashirama face on Madara's chest. Right now that's his best source of power. That's why Madara sacrificed getting injured.
Tobirama takes this for now. His jutsu levels are way beyond Sasukes for now. Tobirama is fast and an extremely excellent sensor, enough to avoid Amaterasu. Experience handling the sharingan genjutsu's. nature wise water takes sauce fire. Stronger than his lightning. Kirin and Susanoo might pull...
Its fairly known but only by most leaders of other villages or philosophers like Oro who wanted to learn about all ninjutsu techniques. Itachi and sasuke really started to make a name of it. Oro surprised? The only thing I remember Oro being surprised about is the totsuka blade
Don't forget Orochimaru and Hiruzen was joking and smiling when the barrier went up... Stating it would take some time for the barrier to broken and for help to arrive. Orochimaru and Hiruzen were capable of breaking out the barrier. Not easily but doable. I'm sure Susanoo could have drastically...
That's nonsense jiraiya was the first person we saw seal Itachi Amaterasu. He had a seal on a paper to stop naruto from transforming. Itachi has totsuka blade already proven to take out an Edo (edo Nagato)
What does it matter there are many fodder on the battle. If the world is going to end might as well go down fighting. If they give up now that would be even more spineless. They are not weak any little bit helps.
If Madara wins everyone loses. Orochimaru is doing what he has to do. Ensuring his survival. He know Sasuke hates the ninja world, and knows he's not the strongest right now.