Using occulations to observe exoplanets is a nifty idea, but like the article says, you'll have rather rare events and a narrow window to do it. It's one of one possible tool to add to the toolchest.
Within in the next ten years, telescopes will come online will allow direct imaging of many more exoplanets than we can do now and be able to see what makes up their atmospheres. Its a very exciting time right now.