Software design is difficult to master and it seems like we either fail to do it, or we over do it. The article does a good job of describing how to get the right mix of design:
Design is good. Design is central to effective software development. Programmers can add features steadily to well-designed software. Programmers can easily test well-designed software. Well-designed software is easy to tune for better performance. Most of the hard problems in programming turn out to be design problems.
But design has a dark side. While there isn’t a single best design for any system, there are many poor designs for that same system. The more experience a programmer has, the more design ideas he knows. The temptation is to put these design ideas in the system now because you just know you’ll need them eventually. Over-designing early leads to delaying feedback from real usage of the system, makes adding features more complicated, and makes adapting the design more difficult. By the same token, under-designing makes adding features more complicated, increases defects, and makes adapting the design more difficult.
The word “responsive” in the name of the project reflects this need for balance. Some design needs to be done in advance of coding, but over the life of the project most design will be done in response to the changing needs of the system and the changing and growing understanding of the developers.