Homura said that they where eventually going to fight, if there is no some sort of fight between both of them, it would be dissapointing.
Also, Homura is doing everything against their will. She didnt ask them if they wanted a new life. It's kind of what happen in The Disappearance of Suzumiya Haruhi. "They got sent from an unhappy life to a wonderful life where they will never be unhappy, but they do not know who it was that sent them there or why they did so, is that something to be happy about?". Of course, its not the exactly the same situation but still nice to keep in mind.
Also, if Homura didn't tell everything to Kyubey, Rebellion would have never happen. Homura shoudl've known better than to tell everything to Kyubey.