Bertrand Russell said, “Mathematics, rightly viewed, possesses not only truth, but supreme beauty – a beauty cold and austere, like that of sculpture.” Analytical models, borne of math and forged with code, should possess the same properties.
A painting, or a sculpture, or a piece of music, is not made better by cramming more stuff into it, a lesson George Lucas famously unlearned. Adding too much to an analytical model results in overfitting, confusion, and mistakes. We must resist this temptation, and move to the next level: viewing the empty spaces as elements that enhance the whole. This is the concept of negative space.
A sales model should account not only for those who do purchase, but those who do not – otherwise you will overestimate the contributions of factors that sometimes generate sales (I am looking at you, Twitter). A scheduling model must consider not only which options are possible, but those that are not. A social model should consider not only those who are active tweeters, bloggers, and commenters, but also those who do their talking off the grid. Otherwise those who shout the loudest in one general direction are mistakenly interpreted as having real influence. There is no truth, and no beauty, in that!