Actually I completely forgot about a big problem with a 21 round (or for that matter, any odd numbered) season - it makes for an unequal number of home and away games, thus also providing another element of "unfairness", as well as providing problems for clubs with less home games than others selling their memberships. I think these reasons alone will kill off any odd numbered length season (not including byes obviously). I also think any draw will also continue to include 2 local derbies for the non-Victorian teams to mitigate the travel factor (which can be seen as another element of unfairness)
This year you play 11 home games, next year you play 10, the year after that is 11, the year after that again is 10.
Stop trying to offer up flimsy reasons to hose down the 21-round season.