Well, that's how the trade off worked. Zangyack would be eliminated in exchange for wiping Sentai from history.
If I recall, they could actually reshape the universe, but they explicitly name Zangyack and only Zangyack.

I kind of agree that they needed to explain the situation a little better, though, but I guess the dramatic tension would have been lost if they spent an extra 5 minutes talking about it.

OK, that makes me far more content with the whole thing. Thanks for explaining!

Yeah if I remember correctly all they really wanted to do was to wipe out the Zangyack and restore the planets they destroyed.

That explains nothing Matrix. The Will of The Earth literally says it can use the keys to do ANYTHING. So yes, it was selfish of the Gokaiger to focus specifically on the Zangyack and not evil at large in the first place. But then to go out and destroy it is not only selfish, but asinine.

Well, because we didn't get much to go on from the episode, it's hard to say. Sentai would cease to exist, though. It's stated as much, at least.

I dunno, for me it's ruined the series. The whole series was building to something which the show completely discarded and for reasons that make no sense at all. It is some of the very worst writing I've seen in toku and it's dropped Gokaiger pretty hard in my rankings.

Lots of people have found ways to talk themselves into accepting the shows flaws - like the pathetic representations of past heroes - but honestly now I've seen how Gokaiger has played out I don't get how you can say it's better than 'just okay'. From Shounen Stock Character Marvelous to the utterly terrible and ineffective villains I'm finding it hard to remember why I ever enjoyed this series.

But they can't use it for EVERYTHING.
Sentai would cease to exist, but villainy and evil would not. That's not just taking the past into account, but the future as well.
Enter and Deboss were both stopped by a Sentai, but the Gokaigers didn't know they would exist. Even if they altered the past so that every villain team from the past 30+ years would be gone, there would still be the future that they couldn't see and alter.

And that's only the future. Unless the Gokaigers created a perfect universe (Which is impossible, by the way, since there are multiple villain teams in the past that hail from alternate universes, thus technically out of the Treasure's reach to affect), using it would, ultimately, be the wrong decision.

But by the same logic, the series explains that only the thirty four sentai would cease to exist. So if they removed all evil, and then one came from another dimension later then a new sentai could still rise. They always do. There have been tech, magic and everything in between.

Didn't they say Super Sentai in general?

Nope.

And by that logic, none of the technological teams should have lost their powers after the great war.
Gokaiger doesn't make any sense. What do you want?

That's what I believed, but it's been a while since I saw the episode.