I have about 30 coral in my 90 gallon tank - two of the coral are artificial SPS - I think they add something to the tank and they seem to be doing better than some of my past efforts with live SPS. The `artificials' are in a high flow area, so there hasn't been any algae problem even after months in the tank.
Yes, there are many gaudy fake corals available, but there are a few pretty good looking artificial ones now, too. I have had a few challenges with sponges in my tank and am considering the purchase of an artificial one.
No one viewing my tank, to date, has noticed that two of the coral are artificial, but I do get teased about the 240 pounds of live rock I have in the 90 gallon set up! I won't be trying artificial rock.
Some of the public aquariums in the world are using many artificial coral in their displays ... partly for environmental reasons. I'm sure it's better than having real coral that die.
I think there may a place for artificial coral in reefkeeping.