Everyone, Paladins especially, loves Paladin auras, so those aren't a problem. The seals... it's not that the Paladin's seals aren't useful; it's that they have short duration. Even if seals are useful, they're very tedious to apply, and reapply. That's the complaint of most testers. Paladins are requested for groups, for a few reasons:
1) Backup healer and rezzer
2) buffs, like the auras and seals. There's a seal (forget the name) that heals players who connect with a melee attack. Dual-wielding rogues BEG for that one.
3) Wipe recovery. This will be more fleshed out when paladins get their new abilities, but the upshot is that the Paladin can survive situations where everyone else falls dead. Then he can rez the whole group, member by member.
Notice something missing from the list: TANK.
Currently, the Paladin isn't a very good tank for more than a duo. It has trouble maintaining aggro, in part because of his low damage output. He's almost impossible to kill, but if the enemy's not attacking you, it doesn't matter. Remember this, however: Blizzard has said that they are looking into aggro management for the Paladin. They're really trying to make Paladins viable tanks. Watch for this next patch.
In fact, ALL of what I've just said only applies to the current moment. Paladins will be getting a huge makeover come next patch, so be prepared for any/all of this to change.