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