People just generally don't understand design or manufacturing at all it might as well be magic to the layman "all you gotta do is..." yeah sure that would make a better product in absolute quality terms, if it's possible at all, but you have to balance it against 100 other things.
There's a reason there are rooms full of relatively high paid individuals with fancy degrees or decades of experience.
And speculative execution is the stuff you do on top of your fancy ALU to make sure you waste less time – so it's not like we haven't already tried the simple idea, but that we've moved on from it