I like this idea for making wild animals better at fighting, however there's something very important you're forgetting: most creatures don't have modified attribute ranges. Like those lions and bears, or even dragons you've been using as an example just have default attribute ranges (except dragons, but they have high willpower which I don't think is involved in this suggestion). I know that attributes are supposed to affect skills as it is, including strength and agility affecting combat skills. I've just made a new creatue which is a dwarf with all of the attributes they normally have modified (which is all combat attributes except endurance and kinesthetic sense) increased to 5000, and I tested it out in the arena against a normal dwarf. I was hitting about 90% of tricky shots and I never missed any attacks of lower difficult. Trying a normal dwarf against a normal dwarf, I didn't get one hit in about 20 attempts, of all sorts of different difficulties. So, it seems like what you're asking for is already implemented.
However, to make it more like what you want, I'd say you could suggest that Toady goes back over creatures and adds a bit more detail to them. Like actually make bears notably strong rather than just a bit bigger than humans because body size isn't really enough to simulate how much stronger bears are, make big cats more agile, that sort of thing. As it is in game, someone with no skills has basically never even heard of the concept of combat. I imagine they'd swing a weapon around their back in an attempt to hit the enemy in front of them. With no skills you're not hitting anything, even another thing with low skills.