Let's face it, ep7 is a reboot of a franchise. Disney just learned from Star Trek and 007 how to avoid a complete/hard reboot but still get a tons of cash out of it.
For a reboot, a familiar setting / story / background is essential to hook the old fans and to capture new ones who have little to no knowledge of the franchise. There is no way on earth Disney was not going to play safe on this movie. Plus, this is Hollywood (and Disney) we are talking about. How many comic adaptations, reboots and sequels have we seen in the past 5 years?
For Disney this was a cash grab with a hard deadline of 12/18 (lol at you who thought JJ had a choice to move this date up or down). Like it or not SW is now part of Disney merchandising machine. Safe familiar stories are the keys to get as much money out of consumers' wallets.
Lastly, Disney knew SW fans are the most illogical bunch on earth, and Disney just love to exploit this. How many of you who complained have seen the movie more than twice? Three times? Four times? Seriously, people who complained about how dull and inspiring Transformers 2 movie did not come back to the theatres to watch it again and again. They also did not come back for Transformers 3, 4,etc etc..
And Disney also know ep8 will be a success EVEN IF it contains scene where Luke says to Rey, "No, I am your father"
ETA: I am actually 85% sure, whoever Rey's dad is, he is going to say the above line to Rey in movie 8
It is all about
(looks like someone woke up on the cynical side of the bed )