I think you hit it on the head. Usability. I'm an IT guy and run a headless linux distro with GPU's, mining one of the currencies. I have Accounts on on Kraken and Coinbase along with my Jaxx wallet and local wallet, that I have to use CLI to send with. I have difficulty using Kraken and if my Jaxx wallet doesn't have the currencies I want as part of the ShapeShift application I have to shift to the web app ShapeShift. Bottom line, it can be a pain in the ass to use all of the different platforms to buy/sell and transfer.

I do like the Jaxx interface and if they can adapt more currency wallets and integrate them with ShapeShift, that would go along way to more widespread adoption.