Guys, come on. The battles are already too long, and the balance is more or less normal. 6 characters in the party are:
1.) will make the passage of fewer characters more difficult;
2.) Will force developers to make enemies stronger
3.) a series of fights will be too easy or too hard
4.) Will slow down the battles even more
5.) you will have to constantly resurrect party members

4 characters in the party are fine with me, IMHO