Dear Jody

'Saya' is used in a formal situation/context. It is also used to speak/write  to a person/people you respect or should respect (the eldery, people in authority and your senior/people in higher position). As Indonesians consider the eldery, people in authority and people in high position should be respected and should be spoken in a formal way  therefore you should ddressed yourself with personal pronoun 'saya'.

I hope this answers your question.

Kind regards,

Sri Wilkinson