This is pretty much spot on.
It's because Lucas has no social awareness. The romances were bad because Lucas doesn't know how to write a believable romance. The character's perceptions and personalities were hard to swallow because they were stale and unrealistic. You'd think, from watching the movies, that Lucas has never socialized with another human being.
All three of the movies are awful from a writing standpoint. They have impressive cinematics and over the top choreography, which is enough to draw some people in, but they are all written poorly.
Episode 1 has no main character and it's plot divulges in to too many directions. The characters and often their actions are hard to believe and it's fairly clear that Liam Neeson didn't give a damn about his role, and I don't blame him. The Pod Racing scene is the only great and memorable scene in the movie, even spawning it's own videogames, but is all cinematics. By popular opinion, Maul is also an up for the movie but Lucas doesn't build him at all and kills him off quickly.
Episode 2 the characterization gets even worse. It becomes increasingly clear that Lucas has no idea how to write believable human beings and nobody on the writing staff has the balls to stand up to him like they did in the original trilogy, meaning most of his ideas go unfiltered. The romance feels forced because it is, it would of taken another writer to make it feel real.
Episode 3 Anakin's characterization finally reaches the point of 100% unbelievability. Nobody around him notices his personal anguish despite how incredibly obvious it is. You don't need the force to see that he's a troubled young man and if literally anybody had sat down and talked to him in a friendly manner he would not of become Vader. Finally the fight at the end is ridiculous, I wish I had that .gif of them twirling the lightsabers around each other for several seconds for no reason. It's most people's 'favorite' because, even though the writing is no better, there's more visual emphasis then there is writing and story and the cinematics are well done for the time.
The one underlying theme throughout those three movies, was that it was just not believable. The originals at least had some authenticity to them and didn't feel forced. I did enjoy the prequels, but undeniably, there was something missing. Disney and an Oscar winning writer taking over the helm is undoubtedly going to improve this franchise.
I would close with "in my opinion", but considering I typed this, odds are it is.