It was shiny and new back then. Unfortunately all shine wears off when it's neglected. The league never grew. It has always just stayed the same and in a few areas we have taken a step back, especially when we look at the ACL. Salary cap has been reduced. The bridge between old and new was never built (eg: P&R). Fewer players transferring to the big leagues and becoming regular starters.
The big change that has happened over the last two decades is the monumental shift away from mainstream media. It shouldn't even be called mainstream media anymore. Network TV, radio and newspapers are all such small audiences now. Social media, youtube/tiktok and podcasts are the mainstream media now, whether we like it or not. The number of eyeballs on those platforms absolutely dwarfs what traditional media has ever achieved. The whole, "market on mainstream media" thing is kinda done. That ship has sailed. Broad appeal marketing doesn't work anymore. Everything is targeted and algorithm based. People don't even visit websites anymore. 20 years ago, you'd have dozens and dozens of bookmarks in your browser, and you'd get your various information from a pretty wide number of sources on a daily basis. Now, on average any individual only uses about 5-6 websites/platforms for their information on a daily basis. Everything has narrowed right down. Our game (at all levels) needs to adapt to this change and become focused rather than broad.
Also I reckon people need to stop complaining that the APL isn't marketing the A-League. You don't hear fans of NPL clubs, complaining that Football Vic or Football NSW isn't doing enough to market the NPL. Primarily, it's the individual club's that need to market themselves, grow their support, get bums on seats and sign up new members.