Jakku is only like a year after Endor though, that's 29 years from Force Awakens, I don't think we know if the battle is even in the film besides the aftermath on the planet so many years later. I'm not sure if it's worrying that they are concentrating on one era of films and still managed to miss so much, or that they are going to ignore the other 60 years of lore on either side of the original trilogy and miss even more stuff they could add. Couldn't even get space battles in....still bitter about that.
Well, like I said, Prequel Trilogy/Clone Wars stuff is a massive amount of content. If they wanted to do a reboot like this, they have a lot of Original Trilogy fans to please. Lack of space battles is a failing in that regard, but overall I think what they have done in making the new processes to develop the areas and give a very true-feeling representation is quite stellar. Since the fanbase is in many ways divided, it makes sense to me to separate content per release between trilogies rather than pick and choose bits from everything.
That said, does it make more sense to focus on TFA content for this first of the reboot? Well, no. And there are a few factors involved.
First, it seems unlikely that Disney would be giving full content access to them to even do that, so that is quite a barrier.
Second, it would mean delaying the game release to come only after the movie, so it isn't spoiling content from the movie. Possible, sure, but money rules all and I'm not sure what their schedules are looking like.
Third, the industry has been constantly growing and new children start gaming after they are born, which is a part of why we get this reboot, not just to please longtime fans of Battlefront. Reestablishing the franchise mindshare on present platforms and their playerbases is key to maximizing profits off the new trilogy.
Fourth, the new trilogy is indeed a trilogy, so that means more content later, content that isn't made or unclassified yet, as well as renewed hype later. TFA isn't their one chance to capitalize on the new trilogy.
Fifth,
as I explained earlier, development is different these days, rolling out installments of a franchise more quickly and responsively to player feedback. Mindshare is also different these days, using hooks in the present installments and subscription services to maximize following installments. So with this in mind, they'd be using this one (and maybe Prequel Trilogy/Clone Wars between) to learn how to make the TFA installment as best as it can be, and to plant seeds in the playerbase to harvest in sales with it later.
It's easier to ask for forgiveness than permission. Lukewarm reception to this installment isn't the death or the waste of the franchise reboot, but instead it will be converted into promises of improvements in the next that they actually will deliver on. It will likely ramp up through a trilogy itself for this reboot, culminating in a Sequel Trilogy focused release of the highest quality and biggest fanbase/hype levels parallel to the third film in 2019 either as a tech-limit-pushing late-gen product or as a cross-gen title depending on hardware cycle timing.