One of the reasons that is may not have worked vis-à-vis the RAD platforms like Access and Excel is that the GUI part always looked polished irrespective of the quality of the program.
But, Scratch programs always looks like toy prototypes, so they never fool the non-technical user into thinking that they built something indistinguishable from what experts do.
Presumably, optimization doesn't necessarily mean making it run faster, but rather is about making is scalable (which means things like cleaning the codebase, addressing security issues, etc.).
Thus spake the master programmer: "When a program is being tested, it is too late to make design changes." -- Geoffrey James, "The Tao of Programming"