Continuing on from my previous post about the role of paladins, I'd like to examine the role of paladins in raids, and why this is a source of dissatisfaction for many paladins today. Two caveats, though. First, I'm not an experienced endgame raider, I have not gone into Molten Core. Rather these observations come from trends observed in non-epic raids, forum posts, and conversations with other paladins. Second, I make the assumption that the paladin is designed for a "5th-man" role, and not one of the three standard roles (tank, healer, dps).
There are two problems, both related to each other, at the heart of paladin dissatisfaction in raids. First, the increase in numbers eliminates the need for the 5th-man role. Second, and more importantly, the paladin's role in raids does not match the player's vision of her character.
To see the first point, lets take the standard 5-man party of tank, healer, dps, dps, and 5th-man. If we expand it to ten people we get 2 tanks, 2 healers, 4 dps, and 2 5th-man. However, the point of a 5th-man is to provide redundancy to the tanks and healers. So instead of taking 2 5th-man, let's take 1 tank and 1 healer. Each can provide redundancy for their respective groups much better than a 5th-man. Boom, we've just eliminated the paladin's role, the one that it was designed for. The ideal raid now consists of 3 tanks, 3 healers and 4 dps.
But that's not all. The need for tanking does not scale with additional numbers. The entire point of a tank is to funnel all damage taken by the group to a single point. Then the healers funnel all healing to the same point. In the ideal raid a single person, the Main Tank, would take all of the damage and receive all of the healing. (In practice, of course, it is much messier, but the ideal is still valid.) So in our 10-man raid, we don't really need the third tank, as the second should provide enough redundancy. Instead we replace the 3rd tank with another dps or healer. (Usually dps, as healers are rare). So the ideal 10-man group is now 2 tanks, 3.5 healers (usually ends up as 3 healers), and 4.5 dps (ends up as 5 dps).
Here's where real life comes into play. There are a lot of paladins and shamans. There are few priests. Of necessity, paladins and shamans are forced into the healer slots in raids. It is important to note that the healer role is not the role that paladins were designed for. The role they were designed for, 5th-man, simply does not exist in raids.
Now why do paladins chafe at being forced into the healing role? Why don't shamans raise the same level of complaints? The answer, I believe, lies in player psychology, and the nature of paladin healing. Another post for another time.
 If you extrapolate these numbers out to a 40-man raid, you'd see that they come very close to a raid that has 5 of each of the 8 character classes (counting all paladins and druids as healers). Hopefully, this is an indication that I am on the right track.