To answer the question posed here about purchasing Rise of the Hutt Cartel:
We'd like to clarify that Rise of the Hutt Cartel will be available for purchase through SWTOR.com/buy only, and there won't be an option to purchase it using Cartel Coins.
Is this something we can expect with all expansions moving forward?
And is there a reason why this was chosen when content like section X is available through the Cartel Market? You already have an in-game store and currency for purchasing things for my characters and my account, it only makes sense to have all purchasable content located there. One-stop-shopping for what I need makes things simpler than having some only available from the site and others available in the game store.
The obvious answer that comes to mind would be that it's to make sure subscribers can't purchase the expansion with saved coins. To that I think that firstly, subscribers who have been saving coins is likely a minority. And secondly it would show that your 'appreciation of [our] loyalty'* extends more than just some fluff items.
*"We appreciate your support of Star Wars™: The Old Republic™. As a thank you for your loyalty to The Old Republic™, we have granted you.."