Looks interesting! There is always a tension between high level paradigms like this and just writing the damn GLSL. glslify is another solution in this space that lets you have more fine control over the GLSL, which is usually way less verbose than a high level API.
One major reason for creating TSL is that it's no longer just about WebGL and GLSL. There's also WebGPU and WGSL which is very different to GLSL. The goal of TSL is to compile to both of those plus any future targets.
