Looks like LW 2.0 is using a 20px font size, and 25px line height, which is in range of what is recommended.
Is "what was recommended" similar to "mistakes were made"? It blames it on someone else, while leaving the "someone else" unnamed.
Existing recommendations about text size (and particularly, about not fitting too much text on a line) do not consider that Lesswrong has a different usage pattern than most sites. There are references dating back to 1971, but I can't figure out if any scientific studies were actually conducted at the time to determine this, and at any rate, printed text is not the web.
Also, beware of using some recommendation just because it's easy to measure.
This is basically breaking the site in order to fit "recommendations". LW 2.0 is bad, and everyone involved should feel bad. It is fundamentally designed around a bad idea.
It is fundamentally designed around a bad idea.
That seems rather extreme. What specific bad idea do you mean?
(Context here suggests that it's something like "the idea that typographical choices for LW2 should match those for the web as a whole", but even if LW2's design makes that assumption and even if it's a bad assumption it doesn't seem fundamental enough to justify your last paragraph.)
What are your first impressions of the public beta?