Bunch of reasons Neoz:
1) Aesthetics - while sps dominated tanks are very impressive, I found that I missed the animation provided by the swaying of softies in the current. Plus I love the wide variety of dazzling colors and morphologies of the soft and LPS corals. Further, there is a large number of exciting new morphs of zoanthids, acans, lobos, chalices etc.coming out of Australia and other areas.
2) time/expense - due to my new life with a mixed family of four kiddies, I don't have the time or energy to meet the more exacting demands of sps corals. I have become a lazier reefer in my old age. Softies and LPS seem much more forgiving in their maintenance requirements. LPS and softies are also cheaper to maintain since I do fewer water changes, only run 175 w halides, and use far less calcium/alkalinity and other dosing elements etc.
3) Been there/done that - Since I already had an SPS dominated tank (for those that remember my 125) I already proved to myself that I can achieve a tank consisting of mature sps colonies. I loved the excitement of watching corals grow from little frags but before terribly long you have large colonies growing into each other. After I ran out of room I started to get a bit bored. Since I had to break the tank down in contemplation of moving to a new house I figured that would be a good time for a transition.
I will always love sps and I continue to maintain about 12 of my favorite varieties.