Alright, first let me say these are just my opinion and I look forward to seeing what the rest of the beta players think. I am in no way an expert, but I do feel there's not the right amount of cross character items.
To start off, I'm sure everyone has noticed that glimmer is purely linked to your account, so every character you have can access it/ accumulate it/ use it. Also, your vault is linked, so items are easy to share.
Here's my problem though, your reputation and marks are not linked. Now, I do get that crucible marks can only be earned 100 per week, and having multiple characters could possibly jeopardize that; however, if you link that counter to all characters that should solve that issue. I also do not see anything wrong with the reputation being linked, unless the reputations affect one another. For example having FWC rep. disabling the gaining of Dead Sec rep. Other than that, every item is level restricted, minus cosmetics.
On the topic of cosmetics, I also believe that ships and emblems should be linked to your account. Why should a person that wants a 3000 glimmer emblem have to pay 9000 to have it on all characters? To me, this discourages replaying as another character.
There is an option B that I have thought of too. Seeing that everything minus glimmer and the vault are not linked, we could opt to only have the vault linked. This would, imho, make it seem like there is less of a disconnect with linked things. "Why is my glimmer linked, but not my marks? Why is my glimmer linked, but not my ships?"
Personally I don't want to use glimmer on my lower level character because I could buy something better for my higher character. Again, this kind of discourages building a new character.
TL;DR If glimmer is linked between characters, many other things should be linked, imho.
If glimmer is not linked, I am content with not linking things. (Glimmer isn't linked = makes the characters independent, with the exception of the vault, which I'm fine with. Reputation shouldn't then apply to all characters because they are independent.)
Thank you for reading.