I've been working with several clients on their transitions to agile–or at least, more agile approaches to their projects. In each case, the managers decided to move towards agile because the technical staff were in their words, “naive” about the project goals. To be fair, none of the projects had a vision or release criteria, so it's not surprising the technical folks didn't understand the project goals.
But waterfall, with it's emphases on understanding up front, helps create that naivete. If you could understand requirements or design up front, then the project is just a SMOP (Simple Matter of Programming). And the testing is just a SMOT, and the writing is just a SMO (Testing and Writing). With a SMOP attitude, everyone assumes the predictive schedules are correct, creating a sense of naivete for the entire project–not just the technical staff. The managers are naive about what the milestones really mean, and everyone's naive about the entire schedule.
But there's an even more insidious assumption in waterfall: that the time to finish the project doesn't matter. This attitude arises even more if a senior manager or program manager or project manager says something like, “Quality is Job 1.” At some point, this project has to end and the product has to ship. Maybe not next month, maybe not even next year, maybe the year after. But at some point in time, the product will ship, regardless of the technical staff's perception of quality. And that's where waterfall lets down the entire project team.
I haven't worked on a project or consulted with a company where they had endless time to get to release for at least 20 years. (I can only remember one project where we were not under time pressure back in the early 80's. But maybe I can't remember much 🙂 Granted, I tend to work on or with projects in commercial organizations, so if you're working on a government project, maybe you have more flexibility in time.
But a waterfall project organization, where you have milestones such as “requirements complete” or “feature freeze” or “feature complete” provide a disservice to the entire project and management team. We know the requirements are not complete. We know the features will change. Saying they are complete or frozen won't change reality. But those complete or frozen milestones provide a sense of inevitability about the eventual ending of the project, and infer that since we're “meeting” (ha!) the project milestones, that we will continue to. That's the naive part. (See There is No Such Thing as Percent Complete and Showing Project Progress (NOT percent complete) for why.)
Waterfall is fine for a few weeks (4 or fewer), and a few people (4 or fewer) and where you're sure the requirements are not going to change. Absolutely, positively sure. No surprises. But if you have a larger project or a longer project or you have a suspicion things might change, you want to work differently. I recommend you read my recent Cutter IT article, What Lifecycle? Selecting the Right Model for Your Project to see ways to organize your projects so they make more sense.
Naivete can be charming in people. But it makes for badly organized and executed projects and programs. Waterfall reinforces naivete. Any other lifecycle allows you to take a more empirical approach, rather than a more predictive approach. The agile lifecycles are all about empiricism, so they banish naivete–at least, about schedule–completely. Choose any other lifecycle, and you can take a mature, not a naive, approach to your projects.