the reasons people take photographs and the reasons people appreciate photographs are often different, but do converge in some areas.
that is the commonly accepted general statement. each individual has a unique perception/passion in each of these areas.
someone once posted a scan of a photo taken of her sister. i immediately knew that i had to have it. i sent an email to her with questions regarding the purchase of a print. she thought that i was a stalker because she had never sold a print. after we worked through it all and she realized the fact that i was genuine and sincere, i had the print a week later.
so i bought a print of someone's sister. a random person. why?
it was technically without flaw. perfect dof, nothing annoying in the frame to detract from the subject, and most importantly; she hit the shutter at the right time. all at once the girl in the photo is happy, sad, being carefree and enjoying the day, being caught in the act of doing something that mom told her to not do. she has the eyes of the unknowing and innocent, she has the eyes of all wisdom. why did she take the photograph? because it was her sister and she wanted to photograph her. i'm not sure she knew it at the time, but she was able to capture that 'other' aspect; the something that makes a photograph live rather than just be.
a visual memory and conveyance of subject are, of course, reasons people take photographs and pull them out from time to time for the sake of remembrance.
others photograph in a technically sound way in order to capture and convey a sense of emotion and presence.
the list does go on. the profession of one of the best current day photographers i've ever known was to travel the world taking photographs of.....food. for magazines. that was his profession. the photographs led a person down a single path of, 'damn, that looks good'. his 'off hours' work was something else entirely. i could stare for hours at a single piece by him and my emotional perception would change slightly and at at times drastically.
and it continues to go on, but in the end, each person has valid reasons to take photographs just as each person has valid reasons to appreciate certain photographs.
**note - i did not do a spelling/grammar check, so shame on me if there are any errors.