Most of the time, I would rather climb a mountain whose peak I can see than a hill whose summit is shrouded in fog.
When you know what you're getting into, you can plan accordingly. If you don't know how much work there is to do or how long something will take, it can often be difficult to find the motivation to get started or, more importantly, keep going.
When I was a child, I used to read books in a purely linear fashion, as many people do. I'd start at the beginning and read through to the back cover. Often, I'd find myself getting bored in a chapter and struggle to finish it. I'd sometimes get hung up on a page or paragraph, overcome with intense boredom and finding the chapter “endless.†Then, I'd turn the page and discover that I only had another paragraph left, and complete it quickly. If I'd known what was ahead, I would have simply pushed through and finished much faster.
Aspects of language learning can feel the same way. We can struggle to learn tenses and verb forms in a language, feeling like the process is infinite and we will never reach the end. Now, I'll often preview a book or chapter before starting detailed reading, flipping through the pages and chapters to get a sense of the overall structure of a book. When you do the same thing for language learning, you remove the fog from the top of the hill and you can sprint to the summit.
For many, the downside to such a transparent approach is the resulting terror in getting started. You can easily witness this in the facial expressions of people seeing Linguisticator's language maps for the first time. Reactions range from wide-eyed excitement to complete terror, sometimes both from the same person! I've heard more than one person say, “That's enough to put anyone off learning a language.†Can you imagine a mountaineering course without any mention or reference to high altitude? It would be a very dangerous course, to say the least. Then again, mountaineering is not for everyone.
A known workload can always be broken up into smaller and more manageable goals, each to be conquered in turn. Set up your basecamp, get acclimated, and start moving up the mountain. How much would it suck to climb a couple thousand feet, thinking you would find the summit only to realize you're not even a quarter of the way to the top?
Unknowns often kill motivation. Known quantities — when overbearingly large — can also kill motivation, which is why initial gains and progress are so important. It's essential, however, that these initial gains are contextualized within the larger process so that students don't get a false sense of security or accomplishment. Too often I see people proud of their “advanced†knowledge after completing gimmicky language programs that “get them speaking quickly.†The resulting fall upon contact with native speakers can be crippling and is often enough to put such people off language learning for good. Rather than tempt students into thinking they're nearing the summit, show them they're getting to the basecamp.