Doesn't matter
I don't care for this "could for everything" approach. I don't want to be tied to the Internet to reach "my" stuff, work or personal. Regardless of any security concerns, what happens when someone else decides for me, that I can no longer have content X, when it's stored in the cloud they can simply remove it at thier discression. Think of the nightmare that is currently YouTube rights violation - poof, video gone. This also happened awhile back with an eBook via Amazon, they just went in and removed it. This happens all the time with "apps" on mobile devices - someone doesn't like it, or it suddenly becomes against policy - poof, gone.
...I don't have any of these problems with stuff installed and run locally.
The one exception, which I have embraced and like, is e-mail as a service (in the cloud such as Google Apps, hotmail, countless others). Reason being that since I need the Internet to function before I can get e-mail, I don't care that if Internet is down I can't reach my email - I can still be productive and do other work, cause all other applications are run internally.