I don't hate the prequels, personally. But I also think TFA and R1 are better than any of the PT films, and when they were released, I think it is fair to say they were every bit as events as the PT. And I don't see how 1 movie per year has anything to do with a movie being good or not. Three years in between movies these days is too long to go in between sequels, if you want your franchise to be relevant. But I can see how over-saturation can be a problem.
I know I often compare Star Wars with Star Trek, and I know I am probably 1 of 3 or 4 people on Nightly that even cares about Star Trek anymore...it's basically a dead franchise at this point, but I think that this is a good analogy in this case.
In 1990-2005, Star Trek was ubiquitous. That was when most of Star Trek was produced: you had TNG (seasons 4-7), followed by DS9 (7 seasons) and VOY (7 seasons), Enterprise (4 seasons), and 1990-2002 had 5 movies (ST 6-Nemesis). Total saturation was reached probably by around 1998, but the franchise somehow limped along until 2005 when they pulled the plug on the TNG films and Enterprise. People did get sick of Star Trek because it became too familiar, and too much was just rehashing what came before. So, they took a 5 year break, and soft-rebooted the franchise. The result was 3 films between 2009 and 2016, with 1 pretty decent film that proved reasonably popular and is credited for reinvigorating the franchise tempoarily, one crappy film, and another decent film that basically everyone forgot about six months afterwards. Nothing really outstanding, with 3 to 4 years in between each film.
Were they events? Maybe when they debuted, but only for maybe a few weeks, because especially with Into Darkness, once buzz got around about it's flaws, it soon became heavily criticized. ST Beyond, like I said, did respectable initially, but the public was largely indifferent. ST 2009 probably enjoyed the most success, but that is probably mostly due to curiosity and people wanted to see how the reboot handled the franchise.
Bottom line: Star Trek became a pop corn flick movie franchise people discard like a finished soda can. I think one of the things that hurt these movies the most is the long wait in between films. With Star Wars, we put up with it for the OT, because those films really did take that long to film, edit, etc. With the PT, it was doable to put out 1 film at least every 2 years, but Lucas dragged them out for whatever reason. It was like he was relying more on the time between the films to make them an event, than the actual substance of the films themselves.
While Star Trek reached saturation in the 90s and 2000s, the Star Trek reboot films, wen the other extreme, and waited too long in between films. It's like they were taking a page out of Lucas' book, and intentionally delaying production in between films to create a buzz. And that's not even delving in to the upcoming "is it going or not going to happen" Star Trek Discovery that has been plagued with delays, the stupidest business decision ever of making it exclusive to CBS all access, the loss of it's show runner due to interference from the suits at CBS, and now we don't currently have an idea when it will air. That dead dog has been dragged around so much, I don't know many people truly excited about it anymore. I know I couldn't give 2 craps, and I am like the biggest Star Trek nerd around.
So I think there is a case to be made that these days, especially thanks to the Marvel Cinematic Universe, if you are waiting more than 2 years in between sequels, you are not doing yourself any favors. Star Wars really does need a film a year, or at the very least, an episode film every 2 years. That all said, I wish we would have got an Obi Wan film instead of an upcoming Han Solo film. That may actually be good, or it could be the first stumble of the Disney era Star Wars films. I, for one, never wanted such a film, and am not excited about it in the least.