Unless you're doing some comparison work as I said, there is no "importance" to it. I suppose there may be some convenience in having to click a mouse or press a key 50% fewer times, but otherwise, its a non-issue.
Comparison work? 90% of the time I'm typing something up in a word processor, I've got a pdf of an article or my web browser open in the other half of my screen to look up information/put down references/etc. I almost never have to write something up that doesn't use outside information in some form.
