Raiding Mechanics being ignored

New to the innovated mechanics of World of Warcraft gear acquiring as I am, I have noticed a few shocking things that may be a symptom of this overall, beautiful new system.

The Random Dungeon Finder: A wonderful mechanic to getting groups together, this tool allows even the least social person in the game to be able to do heroics and get pre-raid geared. All without the help of a guild, or friends outside or inside the game to help you. Regardless of how wonderful this tool is however, there are problems.

One of the chiefest problems I have to come across comes in the Heroic end of queuing for random dungeons. Many players seem to want you to be geared well outside of a reasonable quality for wanting to do the dungeon. I was accosted by one player who seemed to be under the impression that you should have a 6000 GearScore and be wearing 4/5 T10 armor pieces before queuing for a random heroic. This is a ridiculous sentiment, considering that if I'm geared that well, theres no reason for me to be queuing random heroics at all!

Another is the complete disregard for proper dungeon/party constitution. For instance, I witnessed a priest looting trash mobs as the tank was getting pummeled by a boss. The tank was low on health and this priest wasn't even moving to heal him. An utter fail, in my opinion. Or tanks demanding that you not AoE on pulls of 2 or more as it makes aggro difficult to maintain. Or DPSers insisting on pulling ahead of the tank because, "Its only trash." These are enormous problems, (granted they are problems with the people, not the system)

I think it would be wise for people to take advantage of this beautifully designed system. (Thank you Blizzard) However, I also believe that it would be wise for the people using this system to get a better idea for how grouping and party mechanics work.