Skirmish gaming can be a bit different from mass war games. I play both, I love both. Nice looking tabletop, terrain, and figures! What is that ground cloth you used? It looks like one massive piece covered in static grass, but that is difficult to believe. It looks superb!
I agree with dantheman: long LOS's in gunpowder games makes for large kill zones that quickly grind troops into hamburger! It is similar with medieval games featuring bows and crossbows. Long ranged weapons have that, "Reach out and kill someone," quality to them. The poor infantry have to rush the enemy bowmen to counter-attack, but by the time they reach the bowmen, their force is pretty much withered down to very little of what they once were…
I play war games with Army Men figures. My last big game was a beach landing/invasion into a nearby city. The Invader's infantry got chewed up really badly, trying to cover mostly open ground. The Defender's MG's really hammered the Invader's troops. Next game will be a city fight, with tall buildings all around -- Infantry will rule the battlefield, while Tanks, and other vehicles, will largely be sitting ducks, with short LOS, and ranges for combatants will mostly be rather short distances -- up close and personal, with a lot more hand-to-hand melees.
Open battlegrounds have been historical, and typically they have led to many casualties. Short LOS zones are often more close combats, with smaller battles claiming smaller casualties. The fighting tends to be more intense, though, with both sides giving as good as they get (fun for both sides, in a game).
I enjoy any type of fight, but close-in combat is more fun, for me, personally. I like carnage and a good scrum, no matter how it occurs. Cheers!