One point I'd emphatically agree with is this:
I socialize as much with my random pugs today as I feel like I did a couple of years ago, and believe it or not, people are as prone to act as morons now as they were then. To me the random dungeons are the same, but without the 1-2 hours wait of collecting people for the run and having everyone travel to the instance. Seriously guys, do you miss that?Gathering groups for a 5-man was just terrible. It's good to be reminded of this before complaining about the groups the Dungeon Finder assembles.
One question is one I've been thinking about lately:
I've got a friend who, without any special reason, doesn't say much in instances. He never has. I on the other hand talk all the time, even when tanking and healing (which has lead to some wipes). It is naturally a little difficult to do a good job tanking/dpsing/healing if your keyboard is busy typing words. So if you do a smooth run, ie stay in combat alot, there might not be much typing and not much "talking".
I wouldn't say it's wrong to be silent in a random. I used to stay silent during most randoms, and I don't think that was necessarily a bad thing. For other people, I'd rather shy folks come along than that they sit out. However, lately I've personally started making an effort to say hi to everyone and get a little small talk going. If nothing else, it makes things more fun than if you grimly march through and blast pixels to bits without a word. As well, sometimes something really interesting or funny will come up.
As well as those advantages, however, it also increases your chances of success. Suppose you wipe on a boss due to miscoordination. Suppose you see that the tank isn't using cooldowns. Suppose the paladin has a weird choice of auras up. Your group will be better if you can share your insight. When you get ready to share that insight, it's going to go a whole lot better if you have a talking relationship with them. If you don't, then the first words out of your keyboard are going to be criticism, and players will have an initial reaction to blow you off.