I think it's the lack of content. I've heard nothing but good things about the graphics and gameplay. It's just that you really don't get a whole lot for $60 then they have $50 DLC. It doesn't help that Fallout 4 was released about the same time and is brimming with content for $60 (I got mine for $48).
Dark Forces Jedi Knight Jedi Knight 2 Jedi Academy Shadows of The Empire Super Star Wars Super Empire Strikes Back Super Return of The Jedi Episode I racer The Phantom Menace (For Playstation 1) Empire Strikes Back (NES) Rouge Squadron X-Wing Tie-Fighter Arcade Arcade Trilogy Starfighter Jedi Starfighter The Force Unleashed The Force Unleashed 2 Battlefront 1 Battlefront 2 Battlefront Renegade Squadron And by all means BattlEAfront is a success, so please look forward to more dumbed down, sparse content Star Wars games from EA! "What you mean Battlefront 2 had all of the content from the OT and PT as well as having all the content from ROTS when it came out? That's too hard guys! Think of our poor wallets! no one wants a game with that much content! Let alone a single player mode! Let's just rip that out and sell it as a 30$ book instead! More money!" Though even if it had a SP mode, it'd still be just as dumbed down and set pieced based rather than building a world, characters and story. Which means coming out as book has the advantage.
EA and DICE still hear us, even if they don't do as we like. They know what their fans want, but their goal is to make money. I think that the next Battlefront game is going to have the same mechanics, but the game itself is gonna be a lot better. Just think Forza 5 vs Forza 6. Essentially both games are the same, but Forza 6 added the features that Forza 5 was missing.