a) Yes you can. People have been playing some games for decades and even centuries now. As an example, chess does exist since 1200 after JC. Also, even today, people play old school video games that were very well designed, despite not having any "rewards".
b) As already stated in my previous post, there must be various situations with various ways to tackle it. Because there is only basically only one gameplay situation in the current FFXIV, there can only be one matched solution (eg homogeneized classes). But it is a misconception to assume alternatives aren't possible, especially by making the game less battle centric than what current FFXIV is.
c) Fates have always been terrible in FFXIV and the only reasons people used to do it were xp and atmas, but it support what I m basically saying : in FFXIV, nobody would do anything if there weren't any reward because the gameplay is lacking. Would you see people in pagos if there weren't any rewards ? No you won't, and that's why there is a problem.
d) there are several ways to do that, by making daily quests asking you to find one particular monster accros the lighthouse, by making the lighthouse some sort of places where players would have to complete various quests, etc. There would be endless ways to accomplish that, ways that used to exist in games such as FFXI, FFXII, everquest or more broadly tabletop RPGs. And regarding your concern about the so called "time efficiency" of exploration, it could be easily solved by getting rid of that "hamster wheel" reward structure.
e) FFX is indeed a single player games, but FFXI isn't. And FFXI is built upon a very strong battle system, gameplay wise. It would have been possible to make a game like FFXI without all the associated timesinks that were implemented in order to artificially make the players subscribe. As an example, the depth of the group centric battle system can be preserved with the trust system, that allows players to progress as if they were in a group but without having to wait hours to find one.
f) there are no such thing as "old school" or "modern" design when it comes to game design. It is a forgery coming from the PR teams of blizzard when they started to decide game design was overrated (but it did eventually backfire, and hard). Furthermore, I didn't suggest anything, as it is pointless to give any ideas here because SE doesn't give a damn.
When did we talk about warcraft ? WoW used to be a RPG back in 2004 (my figure doesn't cover the lifespan of the warcrafts RTS).