We were on a EPCOT tour a few weeks ago and the guide said that the Wonders of Life pavailion would only be open during the very crowded park times. Examples he used was Christmas week, special events or other times another pavilion was closed. We actually went inside WoL and all the lights were on and equipment was turned on. He said they had to do that to protect the equipment and keep the pavilion from getting musty and moldy.
The reason he gave for the closure was it was a high labor pavilion to operate, with Mission Space and Test Track running it did not receive the traffic needed to keep it running, and it was becoming slightly dated.
So plan on it being closed during your visit unless you hit Christmas week.