Attributing the lack of communication in 5 man dungeons to LFG is silly.
People aren't talking because they know, or think they know, the fights. This, like I mentioned earlier, is because the community has become better at playing MMOs. They use things like wowhead and tankspot rather than fumbling along, asking questions, and figuring out fights on their own.
Also, saying that the content has gotten "easier" due to LFG is also silly, for the same reason really. The average WoW player has a much better understanding of the game than they did years ago. If you look at the boss mechanics for 5 mans, they have gotten increasingly more complex and numerous over the years so, in fact, the opposite has happened. The average pug is just better than it was years ago so the dungeons SEEMS easier because people are using cookie cutter specs that offer the best DPS and they know which stats to stack and how high to avoid going over soft caps ect.
You don't see +spirit/stamina hunters spamming wingclip with a turtle pet and standing in fire so much these days.