Let me put the case for the defense:
The draw, or even the prospect of the draw, adds a different element to a tied game late on that was really evident last week in particular: the shift to winning territory at all costs and being prepared even to rush a point at your own end to go ahead. It creates a different match scenario that is, for me, much more interesting than a cagey wait for the siren to reload and go again.
The idea of just not blowing the siren until another score is new to me and sounds interesting but would probably have logistical issues with the interchange cap: the draw is so rare that you wouldn't hold interchanges back just in case, and if you get five extra minutes without a score at players' most fatigued, then what? At least if there's dedicated extra time you can say there's eight more interchanges for that period or however many they land on.
I am far from advocating "we've always done it this way" - it's a really lazy defense - but for me it's genuinely better than the alternative. Until you get to the finals where you need a result, of course. Now if you really want a break from tradition, play the grand final at night...