Either you're really good at making appeals to emotion or you're lying. Ayane and Helena are basically sociopaths, ffs. They don't think of things like Checks And Balances or law and order.
All they do is put their boots on everyone's necks and expect everyone else to follow in line, making the whole "DOATEC VS Mugen-Tenshin War" complete BS from the get-go.
I'm gonna go with the hidden third option "nuanced perspective" for $500, Alex.
Ayane may come from a strict clan of ninjas, but to write her off as a sociopath in such a cut-and-dry manner would be a disservice - not to mention disrespectful - to her character. She may very well be the most fully fleshed out character in the whole series, Ninja Gaiden included.
As a bastard child of the Mugen Tenshin village, she's been through a lot of shit. And it took a lot out of her to trust the better parts of humanity as a whole outside of Hayate, her mother Ayame, and Eliot as a result of those years of being a social pariah. It also didn't help that she envied Kasumi - and rightfully so - because she was treated way better by the villagers simply for being born legitimately.
As for Helena, I strongly disagree that she's a sociopath. I believe she didn't know who to trust at first in the events of the second tournament, then after being freed from captivity by Victor Donovan during the events of the third tournament, acted accordingly in her own way in a discreet manner. When she realized it was too late to stop him and Alpha-152 was complete, she then decided to detonate the tower along with herself as penance. The fact she had taken accountability to such a degree shows me she's far from the sociopath you'd have me to believe.
Also, the DOATEC vs. Mugen Tenshin war didn't just happen on a whim as you're implying. Raidou's lust for power in the Mugen Tenshin snowballed into him selling out to DOATEC upon knowing he'd be exiled after his infidelity. This knowledge of the Mugen Tenshin's supernatural abilities gave Victor Donovan the opportunity he needed to see his own ambitions of biotechnology through, which conflicted directly with Fame Douglas's vision upon funding the DOA tournament in the first place.
As a result, Fame Douglas had to die, and so did Helena. The latter didn't go as planned, so Donovan's Plan B was to confine Helena or silence her. DOATEC also happened to have a Japanese division with its own military, so they could threaten the village at any time knowing where they live. The Mugen Tenshin's hand was forced, and they had to retaliate at the heart of the matter.
The war was not meaningless. Donovan fucked around with ninjas, and he found out. That's all there is to it.
Now if you'll excuse me, I've got some matches to play. It'll be a while before I come back to this thread again.