Order-dependence of design decisions

When the proggit community was asked for their best piece of Best piece of insight for computer programming/software engineering? some excellent responses were elicited, including this one from hamsterboy:

The quality of the design of a piece of software depends on the order in which you make the design decisions. 5 years from now, the earliest decisions will have the most far-reaching consequences, and will be the most difficult to re-think.

This can be taken incorrectly as an indictment of incremental approaches or, more acutely, as justification for periodic re-design.

Recently I have been working on a port /re-design of a 2.5 year-old product and it has been an absolute pleasure to be able to take advantage of the insights learned the first time round.