First off, art is subjective so of course everyone will get something different out of movies, however I have to strongly disagree with the characters being uninterested. The 3 new main characters (Rey, Finn, Kylo) all have traits which are new to the series. Finn is a solider who breaks through his brainwashing to discover courage and the good within him, Rey starts out as a traditional "good guy" but by the end shows some sparks of darkness that may develop later, and Kylo is a whole package of insecurity and untrained power wrapped up in the shadow of his grandfather, thus creating a unpredictable and frankly fantastic new villain. Also all three have developed arcs which pay off through the narrative, unlike Rogue One where the characters are "stock" at best and flat out non existent most of the film.
I totally get the problem that people have with Starkiller Base, yes it is totally another Death Star. For me it was not a deal breaker since the focus of the climax was on the interaction between Han and Kylo which then shifted to Rey and Kylo. Setting up their characters for the next film. At least George Lucas's saying about poetry, how "they all rhyme" is true for all three trilogy's beginnings with a Death Star being destroyed.