It has been a few years since my blog was on *.wordpress.com, but my recollection is that they opted me in when they introduced the feature and it took me a while to figure out how to turn it off. (Settings -> General, as I recall.)
Appearance -> Extras -> Enable mShots site previews
I am on wordpress now, and just turned mShots off a few minutes ago. I had no idea this feature was causing anyone problems. Open in new tab still worked fine for me.
It's more of an annoyance when you use your cursor to indicate where in the text you are while reading. Or when you just park the cursor somewhere and it happens to be on a link. Quite annoying on articles with a lot of links like this one.
