When you play the game the mandatory party members are a rogue and a wizard. So far so good, thats what every party needs. Too bad they leave at some point of the story.
I created a fighter tank as main char, because non of the default chars looks like a good tank. I also made a cleric, a ranger and a paladin as custom chars. So now I have a tank, a mage, a cleric, an archer and a 2h pala for my group. Great, a very good set up.
Then suddenly the rogue leaves and I have nobody for traps and locks. I continued and gained a level so I gave my ranger trickery skill and opened the chests I missed. Then my mage leaves and I have no arcane caster any more and no one can identify the items I find (the helmet that helps identification was on the rogue when he left).
The default other party members would be a ranger, a cleric and a monk, so you are out of arcane casters in any case.
Unless there is an ingame hint that the game wants you to be a bard (arcane skill monkey that can be a good tank if you build them right, maybe vivi as alternative) the game really wants to kick your ass.
Well, the main story has a certain house to drive you insane, including possible death of companions.