While there are some account-wide mounts, Bennu comes to mind, because this is a roleplaying game it doesn't seem right to have things like Nightmare be account-wide seeing as you unlock through progression.

We also get account-wide mounts from veteran rewards, so theres that, too.

I just can't agree with merging information specific to the character. This exclusivity is part of what makes this game great for roleplay. It's the same logic I use with account-wide house limits; each character has the same set of privileges/rights and having other character effect these whether it be good or bad takes away from the exclusivity.

SE offers us eight characters per world at a price of $2 USD more. Eight might seem like a lot, but SE offers the same exact features you would get if you had one character.