CoolJ
Refugee
Well the only perks I find a must is the ones that open up recipes and stamina. I'm not sure what freedom is to the point you do have to go down certain routes to play the game which has always been the case. Forge is a must, spikes, weapons, etc...Now they are just gated to draw out gameplay which I feel was much needed. For those that don't like gates the modlets can fix that.
I like how people keep saying there are perks that they must have. None of these perks are required to play the game. Your choice of perks does not invalidate other people's choices in perks. When you unlock a perk, it is expected that you will be able to use that perk. All perks are equally important and they should not be marginalized just because you personally would not choose them.
If the game is to be considered balanced, even in the slightest, then there should be an amount of time it can be played without using any of them. Carbonkid is trying to ascertain the state of early game balance by going for a certain amount of time without using any of the perks. If serious complications arise that would be a marker that some things need to be changed with the base state. It is just an experiment. It is one he believes the Devs should do also. So that way, they can decide if those base line mechanics are what they want in the default setting.
I wouldn't be surprised to see hunger, thirst, and stamina metrics relaxed somewhat based on what I have seen in my current game. I chose not to buy any perks until level 10. By that time alone, I was able to decide that those metrics might be a little harsh on the default game settings.