The other thing is that high level optimizations tend to be hard to come by in hardware. Most datapath hardware is not highly fixed-function, instead it consists of somewhat general blocks that contain a few domain specific fused ops. So we either have hardware specifications that are natural language or RTL specifications that are too low level to do meaningful design exploration. Newer RTL languages and high level synthesis tools _also_ tend to be too low level for this kind of thing, it's a pretty challenging problem to design a formal specification language that is simultaneously high level enough and yet allows a compiler to do a good job of finding the optimal chip design. Approximate numerics are the most concrete example of this: there just aren't really any good algorithms for solving the problem of "what is the most efficient way to approximate this algorithm with N% precision", and that's not even including the flexibility vs efficiency tradeoff which requires something like human judgement, or the fact that in many domains it's hard to formulate an error metric that isn't either too conservative or too permissive.