Here's what Ashely has said on the matter in the past:
[quote:fshnqw17]Vulkan is only supported with certain drivers on certain systems with the latest hardware. It's promising, but I doubt it will be on a majority of systems like OpenGL is for a long time to come. If waiting for technical improvements is unacceptable, then Vulkan doesn't fix that. There's also a huge pile of other issues, graphics certainly isn't the only significant component involved.
(The above quote was in the context of the "Time to move forward?" thread).
[quote:fshnqw17]I guess the "higher" reason is OpenGL is kind of a mess, the API is an early 90s design that has aged badly against modern tech. The new generation of graphics APIs like Vulkan, DX12, Metal etc. are all redesigned to work better with modern hardware and allow the drivers to be much simpler, so I guess that might go some way to helping, but that will probably take a few years to start having an impact...
(That one is from 2015).