I missed you guys too
This point had been debated already, it was too complicated to prevent people from removing roofs and it was clearly an advantage so an option had been added to allow regular players to play fair against people who remove roofs on client side. Again it is an option so use it if you want
I personnally dont think roof mode is the worst thing that you can find. Removing walls is much worse for immersion imo (gameplay had been improved enough for healing people behind walls etc). You also have overlay on items on the ground (not that OP but it prevents people from dropping gear in hidden places so it is bad for immersion, especially factionless people). Also replacing characters with bigger size characters to make bigger hitbox, etc...
I don't think no roof hurts the game that much