In order to use Respond as a proper help desk , the email channel needs to support rich text editor to compose longer replies.
Tickets are usually longer and can contain a lot of information to answer customer's query. For example, offering technical support we need to be able to create ordered lists to give customers steps to resolve issues, we need to be able to embed/insert images into the body of the email sometimes instead of an attachment, hyperlink text instead of long weird URLs, etc.
This is the only thing that's stopping me from using email channel.