On page optimisation can be very important in some competitive markets. Where aesthetics / minimalism (especially in relation to "key" words) are a major consideration in (brochure) website design - many big fish can be seen to be losing out to minnows. Image rich and text thin websites are not always optimal. Keyword research is the foundation of an optimised website. Brand guidelines should allow on-page optimisation including title tags - a company's "mission statement" on their website ideally should use keywords.
Minimalism in use of text in brochure websites is often accompanied by maximalism in use of images / video which may affect site speed / UX etc.
In one of my client's market there appears to be a "standard" website design on many sites I'm seeing (noticeable in the near identical top navigation bars seen duplicated across many websites etc). If you want to optimise your search visibility brand considerations should not be more important than SEO best practice - a delicate balance is required (along with other key considerations).
Other related factors can include your trading style and domain name...