Would you rather: Have some untrust for a while but a working mod, or put a ton of your hard work into the mod, then boom someone takes it and runs?
Unless you trust your team, you're not going to get anywhere. Working under the premise that someone is going to steal your stuff is the least productive thing you can do. It would be like driving under the idea that you're going to get killed in a car accident, walking around like you're gonna get stabbed, whatever analogy you want to draw.
The idea of limiting access to content is ridiculous, though. Its really a non-argument for the reasons others outlined here. You don't go about planning a team structure with the idea of trying to account for all these issues - people leaving, delays, asset theft etc, because it simply won't work. You're main concern when you're making a mod should be... making the mod, not holding other peoples hands or making sure that you're always going to be fine with everything you do, because no matter how hard you try, something is gonna come back to bite you in the arse. Create an environment of trust, where people WANT to be involved with a product and won't be motivated to try and use the team's work for their own needs. You'll always get bad apples, but just like everything else, modding is also a game of luck.
Coders as team leader is an interesting one, because the most important thing as a leader is being a good manager of people, and its no secret that coders generally aren't. People percieve the most successful/released mods are ones with the coder as the leader, but its a bit of a misperception I guess. They are successful because they had someone filling the position hardest to find, and someone that could stay for the duration of the project.
And what do you have? Another generic shitty hl2 mod that no one plays, since there's a million of them. They don't stand out like Empires, or Dystopia, etc.
What you're talking about here is a very hard thing to answer. I think I said somewhere in that artice that 95% of mods fail, and of the 5% that don't, 95% suck. We're talking about a very small chance of success here, and you can have the most kick arse idea on the planet, but if things just don't go your way, you're not going to be a GMod or a Dystopia or an Empires. In the commercial world, it would be like comparing yourself to Microsoft or Apple or IBM. There is a 95% chance that your commercial venture isn't going to be anywhere near as successful as those, but it doesn't stop you from doing it.
What it comes down to is... why do you mod? I mod for fun and as a way of building a portfolio to help me get into the industry. When you mod you should be making things YOU like, making things YOU want to play. Building something for other people has less of a chance of being successful. If your aim in modding is to go and be like Dystopia or Empires, then you're starting off on the wrong foot anyway.