Yes, OpenGL adds complexity. Often unneeded, especially for games that are striving for simpler visuals. Like getting a three bedroom house for only one person. It hugely increases the complexity of the whole rendering system, we have to have a special API and drivers for communication with the GPU, and we have to upload data (3D models, textures, etc) to the GPU before we want to render them. Debugging gets a lot more difficult too.
GPUs may be faster, but they come with a cost. Both in price and on the programming side. CPUs have come so far that I can play games like Quake, Quake II and the original Half-Life with ease on my Intel. If the goal is realistic visuals with complex rendering techniques, then yes OpenGL/Vulkan is needed. But for retro-styled games?, not at all. If the goal is to keep the game code as lean and as portable as possible, then software rendering is the path forward. You can code games in pure C, and do whatever you want with it.