1) It is silly to think that the only loot in quests drops from quests and breakables. Breakables?!? I agree with the WoW guy in that regard. In PnP each mob is lootable. It only makes sense that they would be, including junk that noone wants.
2) Open worlds are fun. This allows for impromptu groupings that would never otherwise happen. You need to kill the same monster another player does? You invite him and you both do it at the same time. Its just as conducive to pugging as the lfm panel is. If you're not sure if you're gonna die taking on that nest of baby glass spiders then you better wait until noone can see you or ask someone to help. This is immaterial though, because DDO is not an open world.