I prefer the maximum number of voters get represented in parliament.
The preferential system does exactly that.
What you proposed in getting rid of preferential voting creates a situation where less people get represented in parliament.
To win government the parties require:-
Current system (preferential) = 50.1% of voter support (majority)
Your system (non preferential) = 41% of voter support (not a majority)
The preferential system works fine, and as Hanrahan said " with the advantage that we only vote once".