I wouldn't necessarily go as far as saying "absolutely no strucutres". But Brian's point is valid. If the game is not organized correctly, a milsim turns into smaller games of Attack and Defend around the structures.
Certain structures, hard points, or similar, can add a lot to the milsim experience, though. Holding a hard point can be a huge tactical boost for whichever team holds it. At Brian's field, there's an open field with power lines running through it, that cuts the forest in half. If you can control that field, you can effectively cut off the other team to only half the field. The only way across the field is to crawl or smoke it.
People should have the option to take and hold a stategic point, but they should also be able to go around it (even though most people don't think to bother). Losing an important point will make the game more difficult for your team, and I feel like that's part of a milsim experience. If you can't take a hard point, then there will be consequences for your team.
If your command cannot work out a way around the hard point, then then he's going to have to throw a lot of resources at trying to push through the hard point, thus stretching his other forces thinner.
In many cases, a structure on a field does mean that fights will be concentrated around those structures. But that comes back to the players and game organizers. For those who were at this year's Deadfall: I don't think that Deadfall would have been played any differently if there were structures scattered all throughout the field.
However, if you go by what the common concept of a milsim is (basically just continuous game play and enforced squad cohession), you'll want to have hard points, trails, and the like, for people to fight over. Unless advertised as one of those niche milsims that the WWII guys put together (Brian's games for non-reinactors included), people expect to actually fire their weapon at a milsim. They'll bitch if they're told to sit on guard duty for 12 hours. They may be hesitant to slowly haul through the forest for an hour to get around an obstacle, instead of charging up the trail to eliminate the obstacle.
From reading your other posts, the field you're referring to is also used for scrims, and regular games like that. Those types of players would probably not take too well to "here's an undeveloped forest. Go play CTF". So while Brian's right that structures are just fight magnets at milsims, those are the types of games that most people would expect to play if you advertise a "milsim".
Edit: Lots of replies since I started writing my response here at work with all the interuptions. Desmodus answered the OP's questions as I would.
To add to "why no one else does fields with no buildings": it's because no one but milsim players would play in that field...And of the milsim players, only a subset of them would actually enjoy it enough to play again.
An undeveloped field isn't much fun for scrims (I've organized some on private land. It wasn't that great). It's really only fun for long term games, where there's lots of exploring, hunting, evading, and build-it-yourself type of stuff going on.
In other words, unless you have another use for the field (eg renting it out for camping, or offering private training on it like Brian does), you're going to sink a lot of money into a field that will be used for maybe 2 or 3 milsims, with a very small number of players. There's not much revenue in it.
Last edited by FirestormX; November 19th, 2014 at 12:57..