Software Building vs Software Maintenance

I've been reading "The Mythical Man-Month" in the last few days and I'ld like to highlight here a particular paragraph: Systems program building is an entropy-decreasing process, hence inherently metastable. Program maintenance is an entroypy-increasing process, and even its most skillful execution only delays the subsidence of the system into unfixable obsolescence. So, for all of us working on program maintenance this means that even if from times to times we introduce new features into the system, we should keep in mind that someday (maybe not so far into the future as we would like to believe) the system we're working on will be deamed obsolete and eventually replaced! Isn't it so much better to design and implement brand new systems? Maybe that's why we're so eager to refactor existing sub-systems and sometimes even throw them way and build them from scratch... By the way, this is one of those books that should be regarded as a "must-read" for all software engineers/architects!