Every typeface is a set of decisions someone already made for you. Reading slowly is how you find out which ones you disagree with.
There is a moment, somewhere between the third and fourth revision, when a page stops being a collection of elements and starts being a voice. It is rarely the moment anyone plans for. The grid was settled weeks ago; the palette was argued over and signed off. What changes is smaller than that and harder to point at.
Type carries the argument because it is the only part of a design that has to be read rather than merely seen. A color can be admired at a glance. A sentence has to be walked through, one word at a time, at whatever pace the letterforms allow. Set it too tight and the reader hurries. Set it too loose and they drift.