Untrained means you have no idea what you are doing. Lets take fighting - I am sure the first time someone steps into the boxing ring with someone who knows what they are doing will get their clock cleaned (d4-2). Now, you might learn quick if you have natural ability, but it is a skill, and it must be learned (just like D&D must be UnLearned

). Let take it to another skill - survival (Smarts). If you have no basic survival training, you are not going to survive if you get dumped in the desert. Being Smart allows you to learn, but it does not magically give you all the options.
Plus, you will find them d4's Ace alot in critical situations. That is a great representation of beginners luck.
Finally, the ability scores in Savage Worlds are much more important than in (say) D&D. Agility tricks, Smarts Tricks, Vigor rolls (Soaking damage), Spirit to come off Shaken, and Str for damage. Making them even more important will really skew the game in favor of Ability scores (which pulls people away from taking cool stuff like Edges or Skills when they get an Advance).
Very well put. That is one thing that has always bugged me about D&D, Storyteller, and Shadowrun, dump enough into the attributes, and skills are barely required.
In the real world, when you don't know how to do something (in particular, physical skills)
you don't know how to do something. With natural talent, you might get lucky here and there and learn it quickly, but to start you don't know.
As for the stuff everyone should know in a setting, that is covered nicely in Savage Worlds with the common knowledge roll, which is representative of normal socialization into a given society. It is sublimely elegant.
I'll just say this - after playing SW for about 2 years in a varity of genres after being a dedicated D&Der, the Attribute/Skill link now feels very natural. Its one of those things that is different from other games and people immediately want to change it. "It does not make sense" tends to come from the context of other game experience (kinda like if you intro someone to TTRPGs and they ask "where is the board?"). You can always tell the new people on PEG's boards when they try to convert their favorite D&D setting - they are trying to covert every Feat/Power in the book instead of stepping back and figuring out what really provides the flavor of the setting. They try tinkering with the attributes/skills, roll a d20 for initiative instead of the cards, less Acing, graph back on HPs. All that is fine, but what you find is it strips away the Fast! Furious! Fun! of the game.
I call this 'right tools syndrome', where because they have played with a hammer for so long, every game looks like a nail, when it might indeed be a screw or fine china. And it happens everywhere. Like when WoD was 'the thing' in the late 90's, I cringed every time there was a movie even
vaguely Gothic or supernatural themed, because I knew the boards over there would be filled with people trying to cram that movie into the game.
You know the gamers that have been at it a while over the younger ones, because us old guys look for a system that fits the story we want to tell, instead of trying to cram a square story in an oval system.
As an example, to the Core rules I have only one House Rule
Savage Wolds is the first system I've found where I see no reason for house rules at all. I don't have a one. I use some setting rules in specific settings, but no real changes to the rules at their core. The only game that comes close with the low number of house rules I need is the new World of Darkness, which has only 3 to the core rules, and 5 total when running Mage. (It all relates to making armor into Damage Reduction rather than Defense adds).
The fact that I don't need to change Savage Worlds any for the games I want to run with it and so any new player that shows up can learn form just the book, is one of the reasons I love it so much.