This has been and issue for a very long time and as I know it is not a Bug but a Feature it is still annoying and needs reevaluated.
Quests should just be Quests
We do not need Weekly, Daily, Group 5, Group 2/3, Raid and or what ever other types of quests there are. Quests should be completable no matter what group/raid you are in. So if you are in a raid waiting in Queue or for a few more from LFG channel you can still go about your normal business until it is time to get in the instance.
It really does not get more simple or complicated than this. Could some conceivably exploit this to get a 40 man raid and burn through some kill/collect quests? Yes. but who cares? We need to start bringing groups of players together to work cooperatively if they choose rather than penalize them for trying to group up.
Now don’t get me wrong weekly/daily quests are a cool idea and are cool-down timer or something is fine it is just that quests should be doable regardless of group size.