Fair points, but these seem to be personal problems/quirks that can't really be fixed in game design, unless you make everything strictly group content, even when it doesnt need to. I think it's healthy long term, when newer players can play the wholle story experience solo, like multiple expansions from now. Hopefully they then also streamline it better instead of bombaring you with 100 quests when max level is reached.
The final delve reward: Yeah, that's a solo challenge, like mage tower. It's supposed to be difficult and making is solo prevents carrying.
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Leaders in kingdoms yes. Not generals in armies. There is a reason Jeanne d'arc is famous, because it was absurd for someone so young to be in such a position.
I based my expectations on the character I saw in the trailer in which she looked quite older.