The second largest group of perks (besides combat perks) is primarily about resources and getting more of them. If all of them went to general, attributes (aka classes) would largely be gutted and only about combat. As I said, what you want could have been a good idea if it was a single player only game, but in co-op it would make choosing your attribute/class a very easy decision about choosing your weapon, without any drawbacks or consequences. Instead now you choose weapon AND the resource gathering you are good at. But you can always choose to get them independently, at a cost.
Nobody from TFP has said anything about reasons why any of the perks wandered into general, so all we can do is speculate. I'll give it a try for a few of the perks:
Two perks are of the type "nobody really wants to put points into but they are needed", especially in a group, i.e. they are multiplayer support. Living of the Land for example: Points into LotL seem wasted. especially because the only reward is that you have more work to do than everyone else (in co-op). Same for Master Chef. Though there are a few who actually wanted to play farmer and cook, but they needed to choose strength and fortitude to do both
My guess is that because both of those perks are important for any play but ALSO nobody wants to really drop points into them, they were made virtually cheaper, at least for higher perk stages. Bonus: A single person can do both without spending additional points.
The armor perks. They have been in a strange place as well. Not sexy at all, they don't give any armor on top, just make them use less stamina. In fact so unsexy that many gamers avoided perking into them and instead used primitive armor, because there was not much difference to light armor and it was so much cheaper.
Also the fact that every player, no matter the attribute he chooses, needs some form of armor, but we only have 3 armor perks for 5 attributes. Even if your attribute had an armor perk, certain armors were more expensive to you because the right perk just wasn't in your attribute. A balancing nightmare. I don't think I need to say more, it just didn't really fit together well. General makes armor perks less expensive for everyone and choosing your armor less constrained, balancing of armor less complicated.
No. If I like vanilla ice cream AND chocolade ice cream and the vendor offers no mixed bowl, I buy both ice creams and mix them myself.
My sugar intake (and diabetes level) will be slightly less than a pure vanilla guy, but I get the best from both vanilla and chocolade vitamins.
And you can do the same in 7D2D.
... took like 1.5 - 2 hour for all to meet up finally without console commands 
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