For me, the biggest issue is the tediousness that arises. Sometimes when I'm trying to level up a spell or a weapon, it feels like I'm getting nowhere for hours on end. I realize it works faster if you hit your own guys, but that just seems silly, and usually I get to a point where I accidentally kill my own people. I once thought of running a game where everyone strictly used magic and had shields in both hands, then I discovered that wasn't a great idea.