A typeface is a bunch of drawings that come to life when used as text. The words and their context will differ, and, therefore, the function of the typeface will vary according to the intended usage. A typeface designed to shout news headlines at people rushing about to get to work will be different from a typeface designed to capture the delicacy of a French wine.
Deciding on the function of a typeface is the first question that needs to be answered in a design brief. It will be the principle that guides you (the reader and, here, a designer) to judge whether the design works. It is similar to deciding what to wear every morning. Are you going to the beach or the office? Are you going to a party or the gym?
The thing is, even the most gorgeous high heels are not suitable for a treadmill. In the course of designing, you might draw letterforms that look great but do not perform well when put to use. If you’ve already decided on the intended function of the typeface, then the dilemma of choice is less scary.