Well, well, this is the most stupid topic I have seem in a few years. So, you backed PoE but you are a power gamer? do you want a "Nuke"? (where is this word from? WoW?). These companions are not good builds because they are just common people. If they will accomplish something big, is because of you. They are not leaders of a country of a militia. They are not High Wizards, just average Joes. Are you in real life the smartest man? Are you the weakest man because you "don't need to be strong"? Do you have the best stats nature could offer to do your job? These companions were not MADE by the gods to help you. They will not complete you or complete a party in the best way possible, maybe not even in a good way. They are guys and girls who choose to be by your side.
Mechanically talking, this is made due to factors:
First, You should be stronger than your partners. Because it is not cool for players to say "damns, I suck, my companions could soloing the game and I cant", because of the story (someone with high stats could be a leader, not following you).
Second, if everyone has good builds and high stats where they need high stats, the complete thing make no sense. I mean, if every Mage has 20 int, is like "all spells are casted with maxed AoE and maxed duration" and remove Int stat. Same for everything in the game.
Finally, they did an option for power gamers: Go to the tavern and do your own builds.