As with any software project, optimization is part of the trade-off equation. In those days, that type of optimization was a necessity. You just couldn't build

As with any software project, optimization is part of the trade-off equation. In those days, that type of optimization was a necessity. You just couldn't build a decent game without doing it. It can still be done today of course, but it is less of a necessity. Teams choose to spend that time working on other aspects of the game instead.