- I get too much spam, so I tend to check email less.
- It's not as "real time" as I sometimes need it to be. Sill feels more like mail than like conversation.
- I like to know when people read my messages (I know there's apps that allow this, but it's not ubiquitous)
- I like to know when people are typing (aka, are currently in the conversation)
- Different email programs send/format emails differently. Some seem to keep all the replies attached to the bottom of the latest message in a way my email program can't figure out and collapse.
I'm a fan of email tbh, and I wish more resources were invested in making it better, but I just don't think it lies in the same "space" as instant messaging.