plant life, algae, macro algaes, or plants, complete the nitrogen cycle, filters out all types of bad stuff, buffers and stablizes the system. Caulpera and other desirable algaes use the same nutrients as the ugly algaes and therefore limit those algaes.
I like plants in my display. the only problem I have is that I can not get it to spread. My tang is constantly eating it. I also have tumble weed like gracilaria (spelling) which grows very slowly. and some money plants, shaving brushes, turtle grasses, and ulva. I culture it in a 20g long and transfer to the display as it becomes available.
If you are considering add macro algaae, go for it. To me a tank is not complete, stable and balanced without plant life (in display or refugium).