The problem with that is you never know how long a unit will be out of combat. Another enemy unit could appear as soon as the unit starts autoloading. Taking away that control could be just as frustrating.
That does sound like a problem, but as the system works currently, almost every single reload is done when fighting (the exception being if the last shot of the fight is followed by a reload).
Auto-reloading out of combat gives a much better chance of reloads happening when the weapons aren't in use.
The idea doesn't take away any control; it actually gives players more factors to consider about engaging at opportune times.