As to WHY people are rude in such public places like Fleet or DK/Courscant, I refer you John Gabriel's Greater Internet Frak-wad Theory. In short, normal person (as in everyone, including the OP and his own brand of rudeness) plus anonymity (on the internet, nobody knows you are a dog) plus and audience (what better audience than a hundred gamers grinding through quests) equals...
...Total Frak-wad.
Those of us who adhere to Wheaton's Law (in brief, "Don't be a tool."), will usually provide helpful advice either in whispers or posts here in the forums. I believe the exhaustion that leads to the degradation of communication that is useful and relevant stems from the problem that people incessantly ask for question that are either easily found in game (not the Codex. I have been playing since Beta, and I STILL have issues tracking the Codex) or here in the forums with a simple search. More often than not the rude and snappy answers come when a person asks a question easily answered in Google.