I think we're talking apples, oranges, grapes and pears here. There are so many applications of photography that it is impossible to answer the initial question.
"Portrait photographers" whose function is has been to record the life of a family. Birth, weddings, family get togethers, family portraits etc. These are incredibly important on a personal level to most families.
Journalist, newspaper type photographers that cover our world and bring us a view of other places and people that we would never have seen without them. (Life Magazine, National Geographic, Eisenstadt etc)
Commercial photographers who have in the last few years set the standards for everyone else. They are the ones who do all the advertising photography we see in virtually every magazine and billboard. They influenced what peopel want their portraits to look like, they influenced what peoples homes look like and they influence what people want to think they look like as well as unfortunately try to sell a lot of crap we don't want or need. I believe they are the most influential photographers that there are today.
Fashion, illustrative photographer who also have often set the style and trends of photography and continue to do so. (Avadon Helmut Newton etc)
Landscape and scenic photographer have not only given us a record of the beauty in our world they have contributed to environmental movements to stop our devastation of these areas.
Our blending of these styles of photography has produces many sub styles of photography.
To say that one is more important than the other is very difficult.
I once had a talk with a very good fashion photographer and I told him I loved his work and was kind of jealous of his work environment (beautiful models) and his creativity. He told me that his work is essentially frivolous and irrelevant, and ends up in a magazine that is thrown out every month. He told me that it was I, a portrait photographer, who had it made because I was creating beautiful memories for people that were staying for years on their walls.
I started to think that maybe he was right and if he wasn't, it was still a very satisfying profession.