Why are there no high quality biographies of Leonid Brezhnev? Is this some kind of bias I'm unaware of?
There are English-language Pulitzer Prize winning or nominated biographies of Stalin, Khrushchev, Gorbachev, and even a couple books that take a stab at Yeltsin despite still being so close to the material. Go back further and there are stacks and stacks of quality material on Nicholas & Alexandra, Peter the Great, Catherine the Great, Ivan the Terrible, etc.
It seems strange to me that no heavy duty academic (e.g. Stephen Kotkin) would wade in and try to make his career on someone that had such a big impact on history.
People have tried shots at Stalin and Lenin without ample primary material; even Brezhnev, once, by the journalist John Dornberg (in 1974), a non-scholarly book where a New York Times review understatedly notes "A great deal of interpolation is required."
The opening of the Soviet archives in the 1990s allowed a new wave of biographies, so we got Taubman's Khrushchev (2003). But Gorbachev we never really got what I'd call a top-tier biography until very recently (2017, Taubman again) and that is the same year we also got a (apparently very fine) biography of Brezhnev by the historian Susanne Schattenberg; but it just happens to be in German.
It sounds like the documents needed to make a decent Brezhnev book were only available recently. Schattenberg herself wrote about the 2016 publication of three books of Brezhnev's memos:
Hence the three published volumes present a very special source, perhaps a genre which has never been published before ... what we find in Brezhnev's case are mere memos. Accordingly, the format Brezhnev used to write down his to-do, whom-to-call or what-to-say lists is a collection of small notebooks, pocket diaries, notepads, and loose sheets.
The books are 1263, 1228 and 973 pages respectively. No doubt, with the unearthing of primary sources, there will be some English-language biographies, but they will take some time to write.
(As far as why Stephen Kotkin specifically hasn't dove in, he's still on Stalin, right? Volume 3 is supposed to be out this year.)
Dornberg, J. (1974) Brezhnev: The Masks Of Power. New York: Basic Books.
Magnúsdóttir, R. (2020). The Lives and Times of Leonid Brezhnev and Mikhail Gorbachev. Kritika: Explorations in Russian and Eurasian History 21(1), 207-217. doi:10.1353/kri.2020.0010.
Schattenberg, S. (2019). Brezhnev’s Memos as a Source. Kritika: Explorations in Russian and Eurasian History 20(2), 421-429. doi:10.1353/kri.2019.0029.
Schattenberg, S. (2017). Leonid Breschnew: Staatsmann Und Schauspieler Im Schatten Stalins. Eine Biographie. Cologne: Böhlau Verlag.
Shabad, T. (19 May 1974). Brezhnev. The New York Times.