That's why Larian is making a lot of the decisions they are, like the 4-man party, nondistict party roles, and emphasis on story rather than combat. Every time someone says the word "tank" on these forums I have ro remember that not everyone here has played D&D and so they don't understand they can have a party of clerics and be just fine.
Yeah, I know you are just throwing things at the wall and seeing what sticks but they are going for a 4 man party because --
1) That's what the DOS engine was optimized for. (or not optimized since party management in terrible in both games)
2) It hides the fact that the game has far fewer NPCs than BG2
Anything else is marketing speak.
Yes, you should be able to complete the game with an all cleric party and no one formation should be hardcoded but for me it feels like D&D and BG when you have the classic formation + PC + wildcard. 6 feels like BG and, besides, six is just more fun.
Besides I don't think there are plans to put 6 clerics in the game.
And if they wanted to avoid the BG comparisons they could have gone for another title like Baldur's Gate: Dawn of the Absolute or Forgotten Realms: Rise of Illithids. Which is what some of the original BG devs wanted them to do.
