When content is the focus of a site, as it is with this blog and WPToronto.com, the uniqueness of the design is a secondary requirement to the information being presented.
The ability for users to consume the content they want is your top priority. Pre-built themes, either free or commercial, can step in to handle the design while content gets worked on.
And if it turns out that nobody gives a poop about the content, there’s less loss. You didn’t invest tons of time, or money, in creating a custom design for a site nobody wants to visit.
But what if the site turns out to be a hit? Great content, growing audience. You need something unique, a brandable experience.
No problem there, either. The delightful thing about themes like Standard and Basic is that they also act as a framework to build on top of. The underlying code is maintained by a dedicated team (8BIT or Themify), so the design/development focus shifts from core functionality to user experience and branding.
TL;DR = Minimum Viable Product applies to content-driven websites just as much as it applies to software development.