British Computer Scientist Quotes
The adverse impact on development productivity of requiring programmers to navigate along access paths to reach target data [...] was enormous. In addition, it was not possible to make slight changes in the layout in storage without simultaneously having to revise all programs that relied on the previous structure. [...] As a result, far too much manpower was being invested in continual (and avoidable) maintenance of application programs.
About PL/I:At first I hoped that such a technically unsound project would collapse but I soon realized it was doomed to success. Almost anything in software can be implemented, sold, and even used given enough determination. There is nothing a mere scientist can say that will stand against the flood of a hundred million dollars. But there is one quality that cannot be purchased in this way — and that is reliability. The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich find most hard to pay.
The artificial intelligence approach may not be altogether the right one to make to the problem of designing automatic assembly devices. Animals and machines are constructed from entirely different materials and on quite different principles. When engineers have tried to draw inspiration from a study of the way animals work they have usually been misled; the history of early attempts to construct flying machines with flapping wings illustrates this very clearly.
In the bad old days before MDA, (conceptual) models served only to facilitate communication between customers and developers and act as blueprints for construction. Nowadays, MDA establishes the infrastructure for defining and executing transformations between models of various kinds.