Another way of sayings that is "when you have a lot of ambient light kicking around, the flash sync speed is critical" :-).
It depends on how you work, but I don't think I've ever been in a situation where flash was involved and we needed to freeze a moment that we hadn't planned on limiting the ambient light anyway.
How many people that buy a $30,000, to $40,000 camera don't come prepared for their creative brief?
It's kind of a double edged sword. You can raise the power and get longer durations and I guess with your system sync at 1/1600th but overall your still cutting into the flash, or just lower the power and get a shorter flash duration which probably works out about even.
Or you can buy the new profoto 8's though they have a very heavy draw from the mains and cost more than a space shot. Actually I think most of the pro 8 use is from rentals.
Regardless, it's nice that phase has upped the sync under certain situations, but a bigger innovation would be clean higher iso, as that covers a lot more territory and is much more economical for the whole production.
When it comes to buying and/or renting and how it impacts the production, there is "want" and there is "must have". To freeze action with flash "must have" is a short duration.
We all like new equipment, we all like fun stuff, but now, well it has it fall into the must have category to open a wallet.