Exactly. Rather than spending the time and resources to make it right, they simply dropped it.
Ah, the old "say 'exactly', and then say something completely different" trick to try to fool people into thinking I agree with you... You are banging away with your false assumption that "with time they could have made ranged artillery work"; meanwhile countless people have explained to you why it would be an inappropriate mechanic for Civ4, why artillery should have to risk itself in battle, and why (we presume) Soren decided ranged artillery should be dropped rather than shoved into a game where it is an inappropriate mechanic.