You know, I can agree with the bolded part.
Also, maybe I am in the minority, but...I like having some melee's around when I play my wizard. If I form a group, I typically try to get one melee, one caster, one healer (not necessarily a cleric), and one person to deal with traps (this person may also fill one of the previous roles, too). Once I have that, I pretty much accept whoever else requests to join, unless I know that a particular quest will really need extra melee-power, or casting-power, or whatever.
If I am doing a quest that I know is particularly easy...I pretty much disregard the above and take whoever wants to come along.