Yes, the length of time healing isn't a significant facor in any modern combat situation, it may have indeed been a large factor in historical battles, if you consider repeated conflicts.
As for the evolution of combat blades, there are other factors to consider for example the cost and time of large scale arming. Plus are such weapons always good indicators of quality, consider the modern choices in this regard.
As well, you can find many example of primitive serrated combat weapons as well as modern ones, the Kris for example is essentially a long serrated blade. There was a thread on its uses commented on by Chas on rec.knives recently.
As well, for swords and such, serrations don't work well on any chopping motion, so any blade which relied on that to any degree would have found serrations poor.
As for the tests done by Allen, a plain edge, highly polished can skate over harder synthetic fabrics on a slash type cut, similar as to how it won't cut poly rope. However if you test the plain edge with a very rough finish the tests come out very different.
If you sharpen the plain edge really rough, say 100 grit AO, it will have a much greater slicing aggression, but still won't match the overall greater wound pattern of a serrated blade. Though I would agree with Cougar, that particular aspect isn't overly significant.
The much lower durability may be a factor though, but based on the bone cutting I have done, only metal impacts would be significant.
-Cliff