I feel like I'm missing something.
Throughout the season, many posters on /co/ wrongly predicted that the inclusion of Ashi would mean Jack choosing not to go to the past and deciding to stay in the future. And they whined and called Genndy a hack for (supposedly) going this way, saying that this would make Jack's whole struggle to get to the past and save his family pointless.
Yet now it's as if almost everybody is angry Jack went to the past and prevented the Aku-wapred future, the one filled with misery, aliens and mutants, who weren't supposed to be on Earth without Aku. Did they not realize the future would change as soon as such a big event as the death of Aku happened?
You could compare the sad anons to Jack himself, who didn't realize the whole plan about preventing Aku's future would mean forever changing the lives of everyone who populated it, including Ashi.