The fact that someone can get into your dorm doesn’t mean they should have access to your room. Simply having a room in your building does NOT guarantee that they’re safe. You’re putting yourself and your roommate at risk.
A key weighs a whole lot less than a phone, yet I bet you a dollar that you take your phone practically everywhere. Get a lanyard, put your key on it, and start carrying. It’s time to start behaving like an adult and working to ensure your safety…
I would imagine that in some other forum, there’s a post about a “psycho roommate” who refuses to lock the door, inviting crazies in at all hours. And I can see lots and lots of people agreeing.
How about this: run your ideas by mom and dad-- you want to keep your door unlocked, roommate wants it locked. Let’s see whether your parents share your trust in everyone who is able to gain access to your dorm.