Yes, the site should raise its intellectual standards because the average reader has far higher than a fourth grade education. Why is it trying to dumb down its content? Buzzfeed writes about many complex topics and should approach them by writing in an elevated way. This will benefit its readers.
They should not raise their standards because their writing is meant for the common people that can easily understand what they're saying. If they raise the standards, they might lose their readership because they might see it as too difficult and not even bother reading their articles anymore. It's not meant to be an intellectual website.
Buzzfeed is not an academic journal that people go to for enlightenment on a particularly difficult subject. People use Buzzfeed for interesting quizzes, fun articles, and introduction to news stories of all types, from celebrity baby names to political debates. Raising the reading level would turn a fun and easy to read website into another CNN or Fox News website. Buzzfeed thrives off of its ease of access and enjoyment of reading.
While Buzzfeed is known for its meticulously researched and intellectually challenging long form journalistic pieces, most of the content on the site does not conform to this template. In fact, most of the content on the site is commonly accessed purely for entertainment and ‘time-wasting’ reasons. Therefore there is no onus on the writers of these articles to raise their intellectual standards.