Coating's added print fidelity is not necessary for type-only work. Both matte and gloss-coated papers are thin, allowing for high page counts. Coatings' primary benefit is ink holdout, providing greater detail, denser colors, etc. Gloss-coated paper appears to be smooth and buttery. Matte-coated sheets provide a contrast between the flat paper and its shiny printed images.
Lighter paper reduces shipping and handling costs.
A lighter basis weight may affect performance. Lighter basis weight may have a less substantial feel, affecting perceived value. The end product's thickness will be reduced and show-through will most likely be more pronounced. But unless durability is required of the piece, this difference shouldn't pose a problem. Overlap at high end of groundwood brightness and low end of freesheet brightness permits a move without sacrificing this effect.