I experienced just the opposite and improved on central imaging by moving my speakers farther apart. Not surprisingly, since an equal triangle has been established, 9' between speakers (center) and 9' to the listening position from each speaker. Previously, I had the speakers to close together at 7.5' for aesthetic reasons. It all has to do with the room and unless you're lucky enough to have a custom designed or "perfect" size room, you end up compromising. While I have plenty of room on the sides, I lack the proper amount of depth between front and rear walls. I can get great imaging and sound staging, but I can't bring the speakers into the room far enough to eliminate unwanted bass loading. Now, due to WAF I must find a source for invisible room treatments.
Speakers too wide apart?
Today on a whim I decided to move my speakers closer together. Originally they were 7ft apart. After the move, they are now 5.5ft apart. I sit about 7.5ft away. I was immediately floored by how much better my system sounded. There was a naturalness that I never heard before. Soundstage depth also increased dramatically (which may not be saying much since before I had zero depth). Most impressive was how much more holograpic the music is. This simple adjustment had an incredibly profound affect on my system. As others have pointed out on many occasion here on this forum, it pays to experiment with speaker positioning. In my case, I highly recommend adjusting speaker width.