Sometimes one kicks in an open door. With force, if needed.
Imagine an important business meeting where the company's web strategy is discussed. Boombastic it comes from one of the speakers; "We need a web site!"
Well, yeah; duh! That is a given. Without a web site, no web strategy. This is not really something we should have to talk about.
Search engine friendliness is like that. It shouldn't be something we have to talk about. It's a given. Deciding not to make your site easy to browse and use, whether for handicapped or mobile users or for search engine spiders, that is something that warrants a conscious, clear decision.
But opting for SEO is irrelevant in the bigger financial picture.
SEO is equal to deciding your shop should have a door so customers can enter. They can, but will they? And if they do, will they buy? The door itself probably plays no role in either.
No, to attract customers and to sell, you need persuasion, enticement, attraction, interaction, the right word at the right time, solid advice, a professional appearance. On the web that means you need to talk with your customer about what they want to talk about. Any piece of extra information that can help them decide you and your product are the best way to go to spend money. It can be an explanation of how laptop battery life is measured, what some of the drawbacks might be of buying an iPod (be honest; customers like and reward that), where best to go if they don't want to shop with you.
But first you need that door.