To me FFXIV feels too much like WoW for me to care about it. So you stole a ton familiarity from FFXI and wanted to make a game that follows the same business model as the most financially lucrative MMO of all time. Game isn't good enough? Quick reboot it so that players have a ton of new content to grind through. That way they never get anywhere! Yay! We make money!
"Everything feels like WoW" is getting kind of tired. It's like saying "all cars look like Ford" because they all have four weeks, use a steering wheel to control, peddles for brakes and a front windshield. Some things work well in an MMO, some things don't. FFXIV failed due to SE trying to be "different" and refusing to listen to it's beta testers when they brought up a host of issues. The reason WoW is so successful is that Blizzard is constantly doing market research and figuring out what works and what doesn't, they try to keep what works while fixing what doesn't. Their not perfect but they at least have a strategy. In FFXI SE took a "this is our vision and we don't care what you think". We've brought many things to their attention since 2003 and they've generally ignored them unless they violated the "vision" of the developers. That is why FFXI is failing (in market terms" right now, refusal of developers to alter their vision to meet evolving player demands.

The "reboot" of FFXIV has to do with the server back end architecture. The things they want to do with the game simply aren't possible with their current setup. They need to wipe the servers and rebuild, it's simpler, faster and cleaner. It will result in large amounts of character data being reset or altered. MMO's are just giant databases on the back end where all the data is manipulated. Everything you do in the game is a transaction to that database, movement, combat, monster AI, ~everything~ ends up being a transaction. So their basically rebuilding that back end set of databases to handle different things.