Couple of Reasons....
1) I still need to connect with a Laptop to FTP photos for Smugmug, Clients, Newspaper etc. Some want some weird photoshopping on their photos. Easier to photoshop and boom to FTP when I am out on a laptop, as the Ipad does not have photoshop.
2) The Mifi will connect with up to 5 devices and not just the one internal like my Ipad (when I get it)
3) If I get my wife an Ipad, then rather that two, 30$ charges which equal 60 bucks I am equal with the price of the Mifi.
Just my 2 GB worth
Tom Q