The only thing I wish Disney would do with MDE is allow for some planning utilities for events that are NOT Disney related.
They do have this in a limited way, but I feel if they expanded the functionality of it, they would find that most people just used it and nothing else.
For example, being able to mark booked flights in it, integration with Disney Cruise Lines (though, I'm sure this is coming already), and the ability to add days that are not Disney (yeah, I know they don't want to remind you that Seaworld, Legoland and Universal are there, but they could just make "free form" days that you can add)...that would round the tool out and remove any need of other utilities.
At least in my mind.
I do still use that email account because it's nice to have all the confirmation emails (Disney and others) in one place without having to search through my normal email. Also, it has a list of contacts that has been built up through the years with things like car rental agencies, taxi companies, various disney numbers (including hotel front desk numbers, if I need to get in touch with the hotel directly), etc...