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...Did the sun become a couple of stops darker to compensate and therefore make less endowed flash equipment more adequate?
No, but we did gain 2 or more stops of sync speed...which has the same practical effect.
Back when I was shooting professionally I would have given a lot for an SLR that would sync faster than 1/125 (or 1/60 on some bodies), and a leaf-shutter that would sync at 1/1600 would have seemed like science fiction. (My Yashica was limited to 1/500.)
I think the main players in the portable flash arena felt that -- in a world where clean images at ISO 400 and higher are possible -- high power levels weren't as much in demand as they had been in the past, so they scaled back.
Sadly, we lost ISO 25 and 50 in many cases, and so it is lower power levels that seem most-missed on the big strobes, as several here have mentioned. ND filters help there, but at some cost in the viewfinder and AF array.
The best course is, as always, having a big tool kit to handle multiple scenarios, but of course the bigger the tool kit the higher the investment.