this would be not so much defense of Ilja this time
but i guess it's how capitalism works. He's full-time on his shaders most of the time, and he makes the most of living from that. And you can't sell much to general interested public by publishing "fixed mipmap code" or other backend sort of things. Same with most of the studios these days, can't just fix existing content without releasing new one (and thus have enough funds for fixing old, but more limited time for that sadly). And general public in this case would rather throw money at beautiful rain, reflections and things like that.