Software often becomes hard to read and understand (and therefore hard to maintain with confidence) unless special care is taken when it is created or modified. The feasibility of maintaining a program or system may depend more on the skill of those who wrote it or worked on it before, rather than on who has to fix it or enhance it now. In many cases, "industry standard" techniques (intended to look familiar to the average programmer) are actually poor programming practice and compound the problem. The point where it's safer and cheaper to scrap the whole thing and start over may be reached long before anyone is willing to admit it. This is especially true when a system must be converted to a different environment or after changes have been made to handle the year 2000.
Although standards are intended to improve the quality of software development and maintenance, consistency of style is not as important as the quality and clarity of the code. In fact, outdated standards in many shops have the effect of reducing program quality to the lowest common denominator out of fear that programmers on staff won't be able to learn newer techniques or advancements. This self-fulfilling prophecy is also self-defeating as the best programmers leave for jobs or contracts with better opportunities for professional growth, and such short-sighted companies lose out to competitors more properly focused on quality. Good standards incorporate and encourage intelligent usage of advances in programming languages and other software designed to support higher quality software development. Although there usually isn't time to do major cleanups of existing programs in a routine maintenance project, any additions or changes can be higher quality so that each program actually gets better, rather than worse, each time it's modified. This is especially true with legacy applications written in languages that have been around for years, such as CoBOL, which itself has been improved dramatically to support quality-supporting techniques previously considered out of its league.
Whether we work on your existing software or create a new system from scratch, it will be in better shape than what you had before - better able to meet your needs now and in the future.