I don't see what the big deal is.
It's Dren's server, you don't have to join, you aren't automatically kicked because of a lack of the add-on, you just are vulnerable to being kicked. It's like rock climbing a wall without an emergency rope, you might be able to enjoy it a bit, but there is a chance you could fall off it and hurt yourself, something like that. I'm a bit tired. Besides, he already disabled the kicker because of the OP as he stated in this topic so you can quit whining about that. I can't really say anything about the Ads though.
Personally, I've seen much worse things on things such as clan Source and similar game servers where paying VIP's that join when the server is full automatically eject a non-paying VIP. This is a simple free add-on. It takes 10 seconds to install, and adds useful functions to the game. He doesn't eye rape you or stretch your FOV every 5 minutes, he just does it occasionally and quickly to test the function of the add-on, and will most likely apply it in more practical ways to his deathmatches and team deathmatches.
I'm not trying to get praise or anything from Dren, I'm trying to calm down and reason with the people who think that a supposedly useless and simple add-on is being shoved down their throats and over-reacting with dramas.