In software engineering training, it's useful to emphasize development speed because if what you build does not work, you can go back and review it and debug it and analyze what went wrong. The code gets nicely persisted in a medium where it can be examined after the fact, and even executed again and again in very structured simulations.
In aikido training, something happens and then it's gone. If you rush through it you never get the chance to examine it carefully after the fact. Certain facets may stick with you, but the complete perfection of the moment will be gone and all that remain are traces in your memory.
In aikido training we should move at a speed which challenges our ability to move correctly but not so fast that we cannot maintain full awareness of what's happening.