From a roleplayer's view I'd love to get this too so we get the possibilities to share our clothes information or build a kind of background story etc.
From the addon's dev view I'd love to get this too so we can share our skills, champion point information etc. somehow to group/guild members or give advices somehow.
The negative aspect:
One could maybe somehow start "mallicious" stuff by sending a link which will trigger something in an addon, like "if you click this link the addon will destroy your gear"
![Roll Eyes (Sarcastic)](//cdn-eso.mmoui.com/images/style_esoui/smilies/rolleyes.gif)
This would also be able to do right now so it's not something what addon devs would do. So no worries.
@Zos:
If we can find a good way to do this I'd love to help testing etc.