Writing good copy (text that describes your product(s) or service(s)) is essential to turning "browsers" into "buyers."
One of the keys that will enable you to succeed in generating good search engine rankings is also one that will accomplish the point made above.
Anyone can slap together pages that get decent rankings; not everyone can do that and make a sale.
The lesson? When you hire a search engine optimization specialist or company, make sure that you or they have a good writer on hand.