I was fan of the show since the the early 2000s, my main beef with the ending has nothing to do with him going to the past. The only issue I have with him going to the past was how badly it was handled and the time paradox it formed.
What I said was not related to my feelings on the show but to understand the view point some have when they say that Jack should have stayed in the future. It's the same personal view of how I would deal with a situation if I was given chance. I would never go back and stop WW2 or anything because it would greatly effect history and change the present. For all I know, I could have created a more dangerous future. It's best to prevent the same things from happening in the future than the go back and change the present.
What paradox does it form? Ashi sticks around a bit but then stops existing, presumably like everyone else.
I don't think it was handled badly. Ashi realizes she has the power to fulfil Jack's goal, after 50 years of him struggling, and doesn't fuck around and helps him immediately. Was handled perfectly.
This show has always been fast and things happening and resolving. Dunno why people are upset about it now
And for all you know WW2 happening is the worst future, Jack for sure knows that Aku enslaved the universe, letting that happen and abandoning his goal to stop it from ever happening would be against his whole purpose and the shows purpose and be an all around dick move.
Is Aliens conquering earth worse than Aku conquering earth and every other planet? Doesn't make any sense. You can't get a worse future than Aku rules everyone and everything anywhere. Ever.
By the shows rules he. Is. The. Ultimate. Evil. Doesn't get worse.