Now I will be the first to admit that George's space opera was meant as fun, and there are a lot of questionable plot holes and things where science gets tossed out the window. But some of Scalzi's arguments on design flaws are pretty scathing and lack the realistic excuses I have seen in everyday life in the real world. So here is my rebuttal to John Scalzi...
R2 is an astromech droid (general starship repair robot), one of several models, as established in "The Phantom Menace." Because of his bravery under fire, he was given an award and special treatment by the princess of Naboo. I would imagine R2 would get all kinds of modifications which would lead to his personality and abilities to get spun off the standard astromech personality programming. Like a hacker's dream. We don't know whether R2 has some "posse" that can hook him up with gadgets he needs, repair him, or what. As far as voice synthesis, not only would an astromech not really need one, but everyone seems to be able to speak to him who needs to anyway. And who's to say astromech droids have a far range of vocabulary? Perhaps a lot of it is personification by the person conversing with him. I know I talk to my computers a lot, like, "Windows... really? REALLY? That's an error output? You're just bad programming...."
C-3PO is a protocol droid, probably scavenged from a junk heap, by an 8-year old hacker genius. The original use of a protocol droid was to serve as a translator and ease diplomatic relations with no worries about loyalty. The "cowardly actions" are often the result of a programming routine that says the droid must be submissive under all costs to prevent it from "one upping" and life form it was working with. But C-3PO was heavily modified from the get-go.
Not all weapons have hand guards. Like pole arms, for instance. Okay, you could argue that the lightsaber is like a sword, so it needs a hilt. From what we have seen in fights, saber vs. saber is not like two greased poles sliding around on one another, but they seem to have quite a bit of friction upon contact. I don't think a hilt is needed.
How do you know they are light beams? I always thought they were a kind of energy-to-matter weapon. Lasers would have completely different properties, and the fact they leave blast marks on otherwise featureless surfaces has always led me to believe that the actual "bullet" was some red/white hot piece of matter formed at the tip of the gun.
Landspeeders and other flying vehicles:
Well, as far as seatbelts on land speeders go, seat belts are not worn by people riding open top jeeps in third world countries, either. And sometimes they do fly out. But you learn NOT to. Motorcycles don't have seatbelts, either. The real "WTF" is inertia on star ships. How can an X-wing make a tight turn at such high speeds without flattening the pilot? I mean, a G-suit is only good for about 6-9 Gs before GLOC will cause a pilot to pass out. But give the fact gravity almost never seems affect anyone on ships in outer space, (the droid ship titling wildly in "Revenge of the Sith" comes to mind heavily abusing this), I assumed that there was a generic "gravity/inertia"
Storm troopers are essentially expendable clones. The armor is probably mass-produced shielding to compensate for their terrible marksmanship. They probably wanted something that was easy to make, easy to snap on, and easily replaced. I doubt the Emperor gives a crap how many people die due to poor armor making. But the hidden issue here is that people, like Luke and Han, can easily hide among the ranks in the suits because they have full coverage and you can't see anyone inside.
The unshielded port on the first Death Star was probably a response to the fact when you need the exhaust port to expel whatever it needs to in a hurry, you want a straight line with as little blockage as possible going out. I would imagine that the Death Star was also designed and built by hundreds of contractors, so a lot of details like this get overlooked, especially with a deadline imposed by a despotic ruler. There was probably a conversation or two where this was brought up, but it got tabled for other meeting priorities, or nobody cared as long as they got paid, or the fact this glaring error would have likely resulted in the death of a designer, so he or she might have kept it a secret.
The second Death Star was unfinished, so there were huge security holes everywhere because the Emperor showed up, said, "Whatever you are doing, stop it, and get the weapon finished post-haste." Even Moff Jejerrod said to Vader, "But he asks the impossible! I need more men!" So already they were short staffed, poorly managed, and the station was unfinished. It would be like inviting an assault on a half-finished castle, with construction equipment and scaffolding everywhere. And having an undermanned army of newly-trained, unproven soldiers. The Emperor needs a throne built in an finished area where he could view the rebel fleet getting blown up, and probably there was this balk, "we have something near a huge shaft. We can built scaffolding and walkways, but it's not exactly safe..."
I would imagine this creature has a very low metabolism, and whose to say Tatooine desert is completely dead? Even the dunes of the Sahara have a lot of life roaming around. And tossing someone in the Sarlaac would be enough to feed it a lot and let it grow very large. I am sure Jabba was not the only mob leader who used it or another Sarlaac.
That Asteroid Worm Thing in Empire Strikes Back:
The Wookipedia lists this as an "Exogorth," or a space slug, and states that it is a silicon-based life form that feeds on the minerals of asteroids, various stellar energy fields, and mynocks (another silicon-based life form). The history of them mentioned genetic manipulation as a form of a biological weapon: "the exogorths could be sent through hyperspace to a specific system. Once there, their increased rate of growth and division could lead to destruction of space stations, asteroids, moons, and possibly even planets." But they fell out of favor when it was quick to realize the enemy could take them and send them against you, and they were hard to contain once they got rooted in a system.
While this seems like a lame reasoning, I read the Wookipedia entry on it, and part of me wonders if this could be categorized as "boldily humors" as the medieval people saw it?