Yes, the ranges over the course of the various TSR editions changed. However, the thing is, those ranges were created not with an eye to historicity, but with an eye to balance. Yes, AD&D had balance, and quite good balance when it came down to it.
A sling had a long range in game, and that was done to balance it out against it's relatively low damage. It makes it a viable choice for somebody who's restricted from a long bow (a thief or a mage or a cleric) and still wants to get some good range in. It brings it on to some sort of parity with the long bow. Decent range, but sucktastic damage (though sling bullets could do frightening things).
Of course, there were also just flat out silly things from time to time, but they really didn't impact the game overly. As a group, you had to decide when this issue popped up which set of ranges to agree to and just settle down on it. I.e., not be massive jerks and just agree to compromise. That's what the DM's job is in prior editions. To impose some modicum of consistency of rules calls.
Are the more hard codified ranges of 3.x "better"? I don't know. I've never played that game to any great length (I think maybe 4 sessions en toto), so I can't speak educatedly about them. I will say, though, that they obviously have some benefits and some drawbacks. I will say that I look very down upon what 4th edition did in some regards. Objectively so. And missile weapon ranges is one of those things.
That, and measuring distance in squares. That particular fetish needs to die now.