[thejeff]

Of course, if you lower yourself to eye level you also couldn't target archers behind the lines, which works just fine.

Seriously, a "don't shoot if there's a reasonable chance of hitting your own guys" default is far more realistic than the current system, where the archers will happily target the one closest enemy running away halfway across the field surrounded by your own troops. If you're thinking about line of sight, they shouldn't even be able to see anything other than a cluster of his own guys.