Not sure if this has been added yet but I would love to see more development done to the email builder interface. The builder we have now is similar to Mailgun with 6-8 buttons. I would love the ability to add more custom info like adding html blocks to embed information, add polls to the emails like ConvertKit has (I believe they are the ones that have this), and other features to have emails be more engaging.
Probably missing some other ideas but thats what I had for now.
Update: Looks like ConvertKit doesn't have polls, they have other things that I don't need want. I was thinking of ConstantContact which does have polls (https://knowledgebase.constantcontact.com/email-digital-marketing/articles/KnowledgeBase/9492-Insert-a-Poll-in-the-Next-Generation-Editor?lang=en_US). Looks like MailChimp also have polls (https://mailchimp.com/help/send-a-simple-poll-or-survey-to-subscribers/)
Would be cool to also have the ability for customers to link to their stores like in ConstantContact and allow them to embed their store products. Could be similar to the work that Klaviyo has done. I know that is probably an large undertaking but thinking through the possibilities I know there are some people I talk to that want me to manage or help them save money on ESP stuff and the features Klaviyo has most ecom uses so perhaps some dday we can see similar functions built out for ED.