I kinda get why this hasn’t been done yet. What would be the point of going to the Hall of Monuments if you can just as well easily access it in your tab.
The thing is though, the only characters I actually use these skins for are my low-levels. Since they so frequently get new and better weapons from drops, it gets really annoying to keep having to port to the instance and run all the way back into the hall just to get 1 or 2 skins.
How about making HoM-Rewards accessible in the tab once you have traveled to the HoM using the portal stone with a new character, so that new players have at least seen HoM once?
It’s just a minor thing but it would be cool if something like this would be added.