Vidu,

Yes, in story dungeons DPS have virtually no responsibility or impact on the groups ability to clear content. That's why a lot of new players play DPS specifically; there's a general understanding that a Tank and/or Healer need to at least somewhat know what they're doing. It's why queue's for this content are usually stuck looking for a tank or healer. It's just the nature of MMO's.

Not getting into whether or not that's fair, it is what it is. The fact still remains that it's trivial content, and can be completed easily even if new players (who play DPS) don't know what they're doing. I get that you have this concept that everyone needs to be trying hard just "because," but that's not how this content was designed. It's only for fun, pure and simple, and it's perfectly accommodated to people who want to have fun without being too serious about it.