That would be useful so that good coding practices get spread more efficiently amongst the users.
If the users can just pick who will review then they might end up choosing people who agree with their ways of doing things: good or bad. So allowing for random reviewer would help. Even better if the algorithm would not be random but would just find a way to cover reviewers who have not reviewed the users code before.
I noticed the Custom workflows
under Edit project
but I do not see any option to assign randomly or programatically, unless a regex can return randomly.
In Custom workflows, there's a trigger to "Assign review participants automatically". There, if you add a bunch of people, then you can assign either all, or N random out of the whole bunch. See screenshot: