Auto-kick truly is a godsend. Gone are the days of kicking again and again those assclowns who make it a game to insta-rejoin. I second Stef's suggestion for some sort of 'ping' notification.
To make it slightly friendlier I also suggest to kick only those with a rating less than 0.99*ratingThreshold, as it's especially dickish to kick someone who's one win away from meeting the requirements. I've already had someone get pissed at this in public chat, and I just don't like to evoke negative emotions for no reason.
I switched from Chrome to Firefox specifically for the auto-kick feature, but Goko seems to be way slower and less responsive in Firefox. Fortunately, I found a way to run greasemonkey scripts in Chrome, via the
tampermonkey extension. So far it's working well.
Also, would it be possible to filter the player list in each room such that it only displays players with a high enough rating (without you having to first host a game perse)? I like to check out different rooms for familiar faces, but scrolling through the list is quite a hassle.