Main Scenario Restriction Bloodstorm - Very Very Bad idea.

[Bourne_Endeavor]

So you're never raising someone, you don't use Aero to let damage tick while you heal, nor Cleric Stance, nor Esuna, nor Protect, nor Medica ?

Cleric Stance is click and forget, Protect you should only use once at the very beginning of the dungeon, Esuna rarely ever has any use and I scarcely need to use Cure, let alone Medica. Likewise, Aero is okay, but things usually die way too fast for it to matter. You will be using Stone I and Cure almost exclusively throughout Conjurer. Lancer is even worse, wherein you literally do nothing but hit Heavy Thrust then spam Impulse Drive until it drops. If you bothered to level Pugilist, you'll have Internal Release however that hardly breaks up the monotony. Thaumaturge mostly boils down to Fire/Blizzard and Transposing between them. Pugilist probably offers the greatest variety because you actually unlock a full combo early, have a couple buffs and need to consider positionals. Otherwise, no, I didn't learn anything playing the classes I couldn't have easily picked up with less than an hour of play. There is a reason the devs have not only acknowledged their dissatisfaction with classes but are basically phasing them out entirely. Come 4.0 (or perhaps sooner), you won't even need to level them for cross skills.

On a market where every MMO follows the same rules, doing things differently is exactly something to be proud of, especially if you're successful.

Not if you're being different for purely the sake of it. Gating content behind the story isn't some ground breaking accomplishment. It's just forcing people to spam numpad 0/mouse click if they aren't interested in it.