Spike technology has developed very little in the lead up to super shoes. The only thing spikes from mid 2000s differ from spikes in the 50s or 60s is weight. The shoe isn't making you run any faster - it's just not slowing you down as much. The spikes I wore in the mid 90s are literally no different from the spikes they were using in the 70s and 80s. Nylon upper, half-inch of foam, plastic spike plate.
It was inevitable that all tracks would eventually convert to all-weather for the same reasons that we no longer drive on dirt roads... maintenance! All-weather are much easier to maintain and the surface makes it much easier to run on during inclement weather (hence the name). But are all-weather tracks that much faster? BU has been around for years, but only recently have we seen a dramatic increase in times.
Here's some fun facts: Ryun and Clarke competed on both cinder and synthetic but never ran as fast as they did on cinder. Ryun's 3:51 mile WR was finally broken by .01, 8 years after he set the record and 7 years after all-weather tracks were introduced. Clarke's 5,000m WR was broken by less than a second 4 years after all-weather tracks were introduced and his 10,000m WR was broken by only one second - again, 4 years after all-weather was introduced.
Is all-weather really that much faster than cinder? Maybe, but the stats don't really show it. Compare and contrast 60+ years of running tech with what we've seen in the last 2 years.
63 US runners broke 4 last year. More than double that of any previous year. US sub 4 times had averaged around 30 the 10 or so years leading up to super shoes. Already this year, 29 US runners have broken 4.