Did they ever address this on the closed beta? This is my #1 complaint with the game. I'm out exploring. I come across a solo dungeon and I go inside. Inside i'm greeted with about 30-40 players in a small area, more players than monsters. I run to the end of the dungeon without seeing a single monster, at the end there's a large group of 15-20 people, camping the end boss to "complete" the dungeon. As soon as it spawns, it dies instantly. Dungeon completed.
This is very very immersion breaking and totally kills, what should be, one of the best parts of the game.. dungeon crawling! I figured this would stop after I got higher level, but even at level 15 it was still happening. I feel they need to cap these at 2-3 players each instance, or even offer a solo version of them.