Re: Should Madara have even been revived?
Madara is obviously pretty confident in the Juubi's ability to do work for him... he's having fun playing with his new toy. That's just the kind of guy Madara is.
Would DBZ have been more entertaining if Cell/Buu did everything in their power to eliminate all potential threats as quickly as possible? Of course not, it's better to watch the heroes struggle to power-up and find a way to beat them. And power-ups need to occur at dramatic moments, and a series like Naruto takes time to built those up.
Might as well ask why Obito didn't capture Naruto sooner, or why the Akatsuki didn't just go demolish entire villages as a team instead of getting caught individually / in pairs where they could be defeated relatively easily. Might as well ask why Madara took his sweet time beating the Five Kages, who were eventually off-panneled. Might as well ask why Haku watched Zabuza lose round ond instead of helping. There are always things chatting are more practical that could be done in a story like this.
For the record, I find Madara to be a fun villain, very DBZ style... less complex than some, but his backstory explains a lot of how he became a obe-dimensional evil dude... he just stopped caring.