That's still nothing to do with Play Online, the problem was with the Square Enix Account Management service. Which is what we still use today, except now it has the mog station wrapper on most of it, but you can still get to parts of the old system if you click on some of the account management options.
You claimed it was "not suited for the current market", and yet it is doing fine in the current market.
Real elemental affinities require you to know what spells to use and can allow for more depth to the combat than just mashing 1-2-3 on every enemy. Eureka is not a real elemental system, it's a very simple system where you just lazily match the color to what it tells you to use.
FFXI's combat has never been tried here, so that's not really relevant.
As I said, FFXI had mounts since
2006. And 1.0 didn't have chocobos of any kind at launch, not even rentals.
1.0 had no sidequests at launch. It had story missions and guildleves. I believe sidequests were added in patch 1.16.