One of the biggest reasons so many startups moved (or started) in the Bay Area was because VCs didn't bother traveling and funded mostly local companies.
Has that changed?
It's not that they "didn't bother traveling". That's inverted logic.
They would go to where the best ideas are most likely to be. Where are the best ideas most likely to be = SV.
You might instead ask: "Why are there unicorn ideas that are unwilling to present a slide deck in SV?" That would be harder to answer.
Eventually too much of such cycle would give way to the increased cost of living. But I see a tendency of more moderation in employee compensation by big companies, which would favor small startups again around the area.
VCs will travel for a great opportunity. If they cant recognize it then they are not good at their job :) (like a lot of VCs)