The standard old-school interpretation -- my interpretation, too -- is that the attack roll does not represent a single attack. It abstracts several swings, thrusts, feints, parries, and dodges into one roll, which determines if all that activity resulted in a potentially fatal blow.
The usual objection to this, from blow-by-blow advocates, is that missile weapons don't work that way: you lose one arrow per attack roll. But that is easily fixed.
Or is it? Crossbows seem to be an irreconcilable exception, especially the heavy crossbow, which can be fired only every other round. Of course, maybe that's only in the blow-by-blow versions of the rules, like Holmes Basic. I haven't done a survey of the way crossbows are handled over several versions.
My initial thought is to just let that be the downside to only wasting one arrow per shot, max. But I thought I'd open up a discussion about it anyways.