I really like side conversations, and I use them whenever I can. It is really nice to have mails pertaining to tickets be part of the ticket instead of being part of my inbox and lost to everybody else if I forget to add it somewhere accessible to others.
However, the "just plain text" restriction is a bother: If we share thoughts that are easily expressed graphically or by an image, it is kind of hard to describe these items in sufficient detail and short.
In addition, even if HTML cannot be sent out of Zendesk, nobody can prevent the recipients from replying using HTML (or rich text for that matter).
Replies are taken in with full formatting, including pictures, etc.
Are there any plans to extend the capabilities of side conversations in that area?