I really like the inclusion of basic graphics routines. Not a lot of languages include these out of the box and it's something I've really missed since I first started toying with programming in QBasic.
It's kind of surprising to me that the language is directly tied into OpenGL given that it's a cutting-edge experimental new language and that seems more the domain of Vulkan.
It's not tied to, it is implemented in it. I could swap out the rendering code for Vulkan, an no Lobster users would need to change anything.
Also, have you actually programmed in Vulkan? Even a simple primitive can be hundreds of lines of setup code. In Lobster they're often a single line. A direct mapping would not make sense.