What I meant is not things like OTRAG (which was an abomination indeed), but practical configurable launchers unified to the certain degree into a family. Think

What I meant is not things like OTRAG (which was an abomination indeed), but practical configurable launchers unified to the certain degree into a family. Think Delta IV, Atlas V, Angara, or even Falcon 9, which is the only surviving rocket from the family that was originally planned. The reason modularity of that kind wasn't especially successful isn't the tyranny of the rocket equation, but the economy. Turned out the launch market is too small to capitalize on fringe cases, and the added flexibility simply haven't outweighed the loss in efficiency. When the modularity was starting to pick up steam, most thought that the market will expand much faster, and few people expected Iridium to be a miserable failure, for example.