First, I'd like to commend you on writing a post that conveys your irritation in a way that retains a well written criticism. It's concise, logical, etc. without resorting to rants or other such barbarism. Cheers.
Regarding Hashirama, he's different than everyone, including every Senju. Tobirama and the other Senju for whatever reason don't have the Yang-release. I think this has to do with a generational effect of Madara/Hashirama being near reincarnations of the sons of the Sage of 6 Paths.
Recall, both sons are incomplete versions of the So6P's as his power was split between them and has never been reunited since with the power of the eyes going to the elder son and the power of the body going to the younger. Thus, if Hashirama wanted to be complete, he'd need Uchiha DNA and a Sharingan, lol. Madara, wanted to be complete, so he went and got Hashirama's DNA and incorporated it at the cost of becoming a ghost/shell of his former self as stated by Itachi to Sasuke and by himself to the 4 Kage when he revealed the Moon's Eye plan.
I would say that the baseline Senju or Uchiha is always incomplete, but I doubt Shisui himself had to wait 10 years for his genjutsu to work again, as that's lame. Ao must've been really powerful or Shisui must've been in a really bad condition to waste a 10 year jutsu on an elite jounin, which leads me to believe he could possibly recharge it in less time. I couldn't tell if that only applied to Itachi or Shisui also.
Nonetheless, I think the whole hubbub is about being complete. As powerful as the Uchiha and Senju are, they're just fractions of the So6P's whose power's have been split since the first sons, preventing either clan and its descendants from ever reaching their full potential.
Madara is attempting to do this by cheating with his DNA tricks and reviving the Juubi, but there's too many things he's borrowing, to put it nicely, at once for things not to go wrong. That's really all that's going on.
This cycle should repeat with Sasuke and Naruto, so I'm a bit confused by Madara's recent actions. Initially, it seemed Madara was determined to repeat this with Naruto and Sasuke saying he would make them fight if necessary (when he spoke to Naruto during the Kage conference), but just recently he said something like, "Today will be the last day that the Senju will of fire will burn" when he set out with his own 6 paths of pain, so who knows what he's up to.
Side Note: Really, the only one who seems to have had both powerful eyes (Rinnegan) and body chakra (large supply + Uzumaki) is Nagato, with a vision of peace through pain and power, but he was crippled at a young age from Hanzou's fire jutsu and syncing with Gedo Mazo. If that hand't of happened, he'd be scary considering how powerful was as a cripple. He's still a bit of a mystery as to how he came to be, and how he fits into the story's Madara has told. Jiraiya has said the Rinnegan appears, according to legend, at times of war and unrest, so I think that that's most likely.
Peace