5 most important reasons to have an SEO friendly website structure
 

It makes navigation easier and allows users to find what they are looking for faster.
It improves the positioning of the website because it is easier to crawl and index.
The bounce rate will be lower and the site will be well seen by search engines like Google: users stay longer on it, as it is useful and easy to use.
Increases the chances that the user will become a regular visitor.
Positively impacts site traceability - search engine robots will find and rank more easily and your site will be more likely to be indexed.