Q:
This is not the slightest bit of fun
Don’t go undergeared and don’t go for power/precision/crit dmg gear, as it’s not the way in this game, sorry.
First, you didn’t ask a question. Using Q: is you asking a question, but you didn’t ask one.
Second, dungeons are just different from the rest of PvE content. You can’t go in as a 5-Signet warrior or a dagger/dagger thief without being incredibly tanky.
Basically, you have to balance your play style with your party. You are no longer alone in these dungeons, and they are designed that way. 5 people running in trying to do as much damage as they can are going to find themselves wiping over and over again. However, a group that focuses on working together, even in the slightest, are going to have a much better time.
For instance, have an Ele throw down a Fire Combo Field, and have someone use a Blast Combo Finisher. Now everyone in your group has a few stacks of might! Using abilities that benefit your group on a whole will greatly improve your chances of success.