Half of the fun of Star Wars movies is the cool outer space battles that they create. Watching X-Wing's dog fighting with TIE Fighters and taking down massive Star Destroyers is cool. However, if one thinks about it logically, it all becomes less cool. The fact is that whoever is designing spaceships in the Star Wars universe apparently has no real understanding of how space works. If they did, they'd build something else.
The issue is that, while many of the Star Wars spacecraft would work well in atmospheric combat, the fact that they're all fighting battles in space makes most of the designs ridiculous. Popular Mechanics points out that since there is no top or bottom in space, building ships that are not perfectly symmetrical is a serious design flaw.
The catalyst for the conversation comes from the release of an image of the Dreadnought class Star Destroyer, an even bigger Star Destroyer than any we've seen before. The ship gets a few extra points for not having the massive multi-story structure on one side of it, as most Star Destroyers do, which makes a lot of sense. However, the ship's design still means that its massive cannons, which drop down from the bottom of the ship (because the ship has a bottom) can't cover an entire 360 degrees, which makes them half useless, since any attacking ship is just as likely to fly on the other side of the Dreadnought. In fact, now it's guaranteed that it will, since there are no cannons there.
The fact that Star Destroyers are all shaped like a slice of pizza would make some sense if the ships were designed for in-atmosphere flight, and while they do that on occasion, it's not their chief purpose. A more appropriate shape would be a cylinder or a disc, as that would allow the ship to function the same way from any angle.
One also wonders why there is still such a desire for the First Order to show they're military superiority through bigger and bigger ships. We don't even do that on Earth anymore, as World War II showed us that small aircraft can easily defeat massive battleships. Also, in the galaxy far, far away, there was a small matter of a Death Star and small one-manned fighters. Twice. Also, Starkiller Base.
Of course, for the most part, this is never an issue because space battles in Star Wars rarely take advantage of the freedom that space offers. They fight on a more or less two-dimensional plane and it seems that everybody in the fight has somehow come to an agreement about which way is up.
Based on the trailer for Star Wars: The Last Jedi, it doesn't appear that much is going to change in the latest entry in the series. We'll just have to do our best and forget everything we know about the ridiculous ship design and enjoy it. It probably won't be a problem.