When our generation was young and in school, we all used to call all people even slightly elder to us as "bhaiya/didi" (north India) or "anna/akka" (south India). Even people who were a year older were called like that and if people below your age call you only by your name, that would be disrespectful. Times have changed. Now people prefer to be called only by their names with no suffixes even by people twenty years younger. There are two possible reasons for this: People are more age conscious and more international exposure/norms. The first is obvious when my female friend and cousin sister dont want to be called aunties by even their 4 yr old niece/nephews. Maybe the popular image of an aunty is a 40 yr old with enough girth that even a baby elephant gets inferiority complex.
The second is perhaps because of the software companies' culture wherein people are addressed only by their first names mostly.
Just an observation and hence no conclusion!