From FT story. Simply answer: because of its weirdly even spread. Unassociated gas, meaning gas not associated with oil, is the future. We always just found gas alongside oil and assumed its distro geographically was similar. It's not. Unassociated gas is everywhere, and this chart doesn't even include methane hydrates (unassociated gas frozen solid in sea beds).
You may think that gas is only so-so exciting compared to oil, but electricity generation is crucial, and avoiding coal is crucial to reduce pollution/CO2. You go mostly gas on electricity to crowd out coal, and then go modular nukes to supplement that (especially where infrastructure is "hostile" in its enviro layout: remoteness is big example), and you use the modulars to make water potable and crack it for hydrogen, and that's how you make transpo happen increasingly (hybrid electricals shifting to hydrogen, with ultralights providing a lot of the energy savings along the way).
Oil has had its time. Gas is the next big node going down the hydrocarbon chain.
The big hold-up/uncertainty on gas remains the enviro impact of fracking. This is why I continue to think that methane hydrates will ultimately be more the answer. But someone please disabuse me of that assumption.