Its all about player immersion and participation. The more such creative content the more a player spends time on a game. These are some features used by many RPG life servers on different games such as Arma2/3 (i was a modder) ,Gta san andreas via MTA client (CIT server has 2000 online players during weekends, 400+ anygiven time), Minecraft, Terraria, Starbound and tons more.
So what’s in common with those above moded servers and Gmod tower?, in a nutshell Gmod tower is similar to a RPG life servers where players have games, events, quests, jobs, vehicles, player trading and player driven economy
So why do you think these wouldn’t improve Gmod tower? If it can be implemented It will give a nice fresh air to Gmod tower.
PS: I understand I went a bit vague about Quest system suggestion, will be re-editing that part.