Microsoft isn't a fan of email bloat, and I think many would fall into the same camp. We're not talking the number of emails here, but rather the clunky and weighty attachments that can come included with some of them. If you're working in an environment where you collaborate often, attachments can become even more [censored]bersome, especially when you download one and realize the sender re-sent and updated copy later on. Again - clunky, clunky, clunky.
To help streamline the entire attachment process, Microsoft has updated its Outlook Web App to allow the sender to attach a file to their OneDrive account, rather than attach it inline. This way, the email will be stored in the cloud, and the sender would be able to tweak it as necessary if mistakes are noticed without having to send a new email.
What makes this feature very cool is that when you send a file this way, the recipients listed on the To and CC line are automatically given access to edit it. That's something that could be configured before (or after) the email is sent, though, in case you only want the recipient to be able to view the document.
Admittedly, I never really found email attachments to be that problematic, but when collaboration is involved, Microsoft's new solution is a great one. So great, in fact, that it's a given that its competitors will follow-suit soon.