Cost-effective Customer Acquisition
There is no payment to the search engines for being indexed. This is important for high volume, low intent phrases which can be expensive in paid-search (eg ‘car insurance’).
It can also be useful for generating visitors on the long tail of search. Many companies bid on these phrases through paid-search, so giving opportunities for those who use an SEO strategy for the tail.
The cost of SEO is relatively fixed, independent of click volume. Effectively, the cost per click from SEO declines through time after initial optimisation costs and lower ongoing optimisation costs. Conversely, paid-search is essentially a variable cost.
Think about that search on ‘car insurance’. The big insurance companies are all desperate to make it onto the first page of Google. The ones that didn’t make it either need to buy PPC ads to be seen, which is expensive for such a competitive search query.
Focus on Web Standards / Accessibility
Designing a website for search is an exercise in designing a best practice website. Search engine crawlers notice errors in your code, so valid code is a must for SEO. And that makes for a healthier, more accessible website. Accessible for Google’s crawlers, and for people.
Customers referred from search engines tend to stick around for longer. Increase customer lifetime revenues via SEO!