Nope nope nope.
Except the "fact" that...it didn't. the 500,000+ numbers was a 1 year blip in I think 2006 (with both WoW and EQ1 still dwarfing it by orders of magnitude) and it has been steadily decreasing every year, it's now at less than 150k...
(I still run into people these days who are big fans of Final fantasy, even going so far as to own soundtracks and action figures from their favorite ones, that still wonder why XI was "never released in the US" and why SE kept the number for XII)
https://fbcdn-sphotos-e-a.akamaihd.n...0a506a622d7999
You may benefit from this reading, especially #8.
On topic, While I'd love to see horizontal progression, it would not fit with FFXIV ARR, not until extension (and with a huge work on the system by then).
Mainly because of the progression during levelling.
Horizontal progression requires more freedom in the character build than what we have. Either a skill tree or more characteristic points per level to create a build. The gear would need to become secondary too, not providing the major part of our stats. Instead it would provide some bonuses, skill increase, set bonuses... things like that.
Difficult to do in ARR