I have generally heard the argument that the fine tuners also have a damping effect in that some of the upper harmonics are ever so slightly attenuated.  Though even top violinists like this effect on the E-string because it tends to sound tinny and harsh just by virtue of being such a thin low-mass string to begin with (and typically the E-string is all steel even if the others are perlon/gut core).  Some people I've seen who have Perfection Pegs still keep one fine tuner on the E string for this effect alone.  I find myself greatly unconvinced by this argument, as I don't think there is any evidence in blind listening research to corroborate this, at least from the viewpoint of the listener.  I can believe that there may be some difference to the player, but it overlooks that the player hears something quite different from the listener.  I also took part in a research project about 12 years back where we took some violins and swapped out the scroll with a guitar headstock...  again, in blind listening, almost no subject could tell the difference, and the ~7% who did all preferred the guitar head mod.  In all fairness, that test was done with cheap violins (probably VSOs by most serious violinists' standards) -- obviously, as an undergrad research project we hardly had the money or the intestinal fortitude to gut really expensive high-quality instruments.  There's been no corresponding large-scale study that actually involved higher-quality instruments compared to what I worked on.  I doubt anybody would be willing to try it, either, considering the investment.

Also, I don't think it's entirely true that violinists are NOT machine-shy luddites if you get into the topic of geared machine head tuners.  Sure, there's the weight argument and the argument of having to damage the pegbox with screw mounts, but those can also be rendered moot either by cleverness or by using something like the Perfection Pegs or the Wittner tuning pegs (although they are more expensive), which still have the precision advantage while still pretty much fitting in like ordinary pegs.  Even otherwise, the weight argument is effectively moot when you look at anyone who does have to deal with it as a matter of course, and simply got used to it.

The single most common argument I hear against machine tuners for violins is simply that it violates tradition.  I look around, and sure they talk about weight, cost, and the time of changing strings, but nothing is more common than this one.  That sounds pretty luddite to me.

Granted, I am The Grumpy Anti-theist and all, so this is a touchy subject for me, but I can't help but fume with anger about that sort of attitude.  "Tradition" means nothing more than it being around for a long time...  but it's confusing old with good.  I don't mean that all traditional concepts are bad, but that tradition isn't a source of merit.  An old bad idea is still a bad idea and an old good idea is still good.  Saying that you don't want to do something because of tradition is just a cop-out for not wanting to think for yourself.