IMO there's no "should" about it. You get the crowds that you deserve. I also think that while any successes of CFG and other CFG clubs have little or no impact on interest in Melbourne City, being what is effectively a football club owned by a State puts quite a lot of people off our club. There is quite a bit of discussion of the future of football in Europe as a result of State-owned clubs such as Manchester City, Newcastle United and Paris Saint-Germain, and also the emergence of the "Big Four" and "Big Six" groups of clubs in various leagues.
In Australia we don't have a big reservoir of fans ready and waiting to buy memberships if existing members drift away from the game and a club. Neither do we have a voracious media to publicise the game and IMO neither do we manage the game well - the GF decision being a perfect example of how to shoot yourself in the foot.