A good grid forces order onto the layout and so acts as an orienting device enabling the reader to knows where to look for information and to understand its relative importance. Just as importantly the grid works on an aesthetic level. Readers might not consciously be aware of it, but subliminally they pick up on the fact that everything is well ordered and in its place. The design should be typographically beautiful, simple without being simplistic, have a clear hierarchy, and have an attention to detail. It needs to be interesting, inviting, and dynamic.
I designed 2 first page spreads of the the article Type Means Never Having to Say You're Sorry by Jessica Helfand.