OMG... here we go again.
I have been wondering this and posting out here about this issue for over a year now.
I remember playing PnP D&D with a party of 2 or 3 and not having a cleric, or maybe no wizzy, etc, and dealing with the most challenging of quests.
It's really no different here. Last night We did the hound on hard with 2 Clerics and 1 Wizzy, a few Rogues, a couple Paladins and a couple of tanks and 1 heck of a guildy bard and 1 of the Clerics d/c'ed as soon as we zoned in and didn't get back until we were opening the chests, so again... that's 1 Arcane, 1 Cleric and 1 Bard and a mix of whatever after that, and we beat it on hard, and in about 12 or 13 minutes. Same group was going to try elite, but people starting falling asleep at k/b.
Honestly, I think it's because people really don't want to be challenged... they want it too easy.
We constantly run parties with no cleric or arcane because people want to work their monks or tanks or whatever and we are just fine.
Modify your strategy to work with the team you built, not build a team for the protoypical strategy (the only one you know or think will work).
What is the old saying??? There are more than one ways to skin a cat... something like that... in this case it's skinning a hound.
*Here's hoping Memnir doesn't put up a pic of a skinned animal now... please don't... haha*
Really though... I have been caught up in the past by looking for someone for DPS and hold out for a Barbarian over say another arcane or whatever and the Barbarian ends up being far sub par and adds no value to the party and costs the Clerics tonnes of mana to heal them. Whereas we could have gone with someone to help buff or heal the rest of the party who was doing what we need.
Open your mind, look beyond the 9 dots and think think think, trust me, it's a lot more fun to do it a little bit different and learn that there are more ways to...
you know...