As to historicity, whether or not there are guards on modern knives is totally irrelevant.
In the 17th century and earlier, it was common for men to carry big fighting knives. There are some REALLY outstanding big knives from the 16th and 17th centuries, particularly from Germany. Fantastic designs, very beautiful big knives that Jim Bowie or Rambo would be proud to carry. Long, wide blades, full tangs, big guards, often with side guards. But these were self defense weapons, not really general purpose (or even hunting) knives. By the end of the 17th century, the big knife was falling out of fashion, and the smallsword became the preferred self defense edged(sort of) weapon. Hunting swords were also often worn. Of course, there are regional exceptions, like Scotland, where they retained the big dirks (without any real guard, by the way), Spain and other Mediterranean areas, where big knives and daggers remained popular. The big fighting knife did not regain popularity until Jim Bowie and dime novels. Think about it: if Bowie's knife wasn't SO different from the average knife, what would be so special about it???
But these are all FIGHTING knives. The guards (if any) were used to protect the combatants hand against the edge of the opponent's blade, not his own.
And what types of knives are really required for hunting? Skinning knives don't have to be all that big, and even modern skinning knives don't often have guards. Many people do their skinning and field dressing with folding knives (just as they probably did 200 years ago). No guards there. For butchering the animal you might use a.... butcher knife :grin:
It took me a long while to get it into my head that the modern mindset with knives (as with SO much else) is very different than it was 230 years ago. Today we have KaBars, Gil Hibben, Randall, and innumerable others. Fighting knives pushed as "hunting knives", and we like to think that SURELY they had the 18th century equivalent of a Jimmy Lile survival knife. But, they didn't.
Personally, I can do with or without a guard on a knife, though I will admit that some guardless designs, like many Puukko knives, are kinda scary, with fat handles and narrow blades.
I find a knife like this one from Scott Summerville to be a nice size and shape for all kinds of cutting work. The edge being well below the handle acts as a guard, of sorts, and keeps my finger from riding up onto the edge. This dropped edge also makes it easier to sharpen, and you get a sharp edge all the way back, which is good for chopping cuts, where a guard would get in the way.