Ooops - I had wrongly considered just the steel/rubber coefficient without allowing for rubber/rubber contact. As the [excellent link to the] Washington State (WS) review shows, studded and unstudded tyres are not dissimilar in braking in dry weather on asphalt.
Differences between the two appear to have reduced over the years because, the report says, regulations around the world have limited the aggressiveness of the studs and because tyre technology has improved the frictional characteristics of newer, studless winter tires.
WS reports that studded tires on dry/wet concrete provide less traction than non-studded tires. This is apparently likely because the studs cannot penetrate the harder roadway surface, which actually lowers the effective coefficient of friction, in much the same way as studded tires lose effectiveness on ice at lower temperatures.
WS report on the 1998 Norwegian meta-analysis on the effect of studded tyres on accidents (meta-analysis is a fancy word for intelligently pulling together the results of a bunch of earlier studies) which concluded that the use of studded tires improves road safety by reducing the accident rate, but the effect is quite small, on the order of 1 to 10 percent. The benefit undoubtedly comes in snow/ice, but modern tyre technology for winter tyres is catching up. Maybe there will be winter tyres for aircraft one day?
I think that some more differences between runways and roads emerge as the discussion progresses, which add to the investigations which would be needed for aircraft studded tyres. The Alaska trials reported in WS were very low speed trials, and I don't know what the difference in friction between studded and unstudded tyres might be at higher speeds. At higher speeds, the time for the stud to "penetrate" the surfacing and grip is less. Perhaps, in the interest of science, someone can run their studded tyre car up to 120 knots (216 kph) and slam on the brakes.
The aircraft tyre load is much higher too. Car loading is typically 0.5-1 tonne per tyre and an aircraft loading is typically 18 tonnes per tyre (737-800) to 24 tonnes per tyre (B747). That might dramatically accelerate the wear on the surfacing and the studs.
Finally there were some new hazards identified in the WS report that result from pavement rutting caused by accelerated wear from studded tire use. First, rutting can cause “tramlining” which adversely affects the directional controllability of a car. However my experience with tramlining on construction joints of asphalt overlays on runways and freeways suggests that this is less of a problem for aircraft than cars (due to more mass and larger tyres). Secondly, when water is present, the rutting allows standing water to accumulate in wheel troughs, thereby raising the potential for hydroplaning. Research shows us that a shallow rut in a runway will allow water to pond. The depth of rut at which ponding starts depends on the runway cross-fall and longitudinal gradient. Since the rut created by studded tyre wear will be quite narrow, the depth of rut for the onset of ponding might be as little as 3-4mm for a 1.5% crossfall runway. This is not particularly high wear. Get another few mm of wear, and the pond standing water can get up to 3mm.
The FOD issue I noted in my first comment still remains, and the WS report notes the problem is a general one. With the extra weight on aircraft tyres noted above, the FOD from surfacing wear on runways remains an important aspect to be considered.
Having said all that, the gap between thought and possibility is closing. Over to any tyre engineers for comments on the tread, compound, life-cycle, repair, weight/speed limit, and cost.