Besides, how would it work as non-drafting? you'd have to effectivly run the race as a time trial- which wouldn't exactly be spectatlor friendly.
And how many 'non-drafting' cycling races have you watched? Time trials are an entirely different event to a cycling race.
Are you against drafting in the swim leg as strongly?
So..why exactly DO they allow drafting?
The run is, at the moment, the dominant part of the race, accept it and move on.
If races were run with no drafting allowed, even only on the bike, then they would have to be time trial style format, to avoid immediate bunching of the pack.