Let me tell you my perspective.

I grew up in Jakarta. When I was in primary 5-6, my friends started using "gue/lu" to sound cool. My parents prohibited me to, as those words sound rude. As a result, I was teased a lot in middle school for using "aku/kamu" when I talked to boys, because youngsters only use "aku/kamu" when they talk to their boyfriend/girlfriend. 

For Jakarta people (at least in my environment), we use "aku/kamu" in these situations:
- Girls talking to each others.
- Girls/boys talking to people who are older or younger than them (maybe around 1-4 year differences).
- Girls/boys talking to their boyfriends/girlfriends.
- Girls/boys talking to strangers.

And we use "gue/lu" in these situations:
- Friends talking to each other.
- Girls/boys talking to people who they're comfortable with, no matter how old/how young they are.

Note: Boys from Jakarta don't really use "aku/kamu" when they talk to their friends because it sounds a bit girlish.

Growing up, I met a lot of people from Surabaya, Medan, and also other cities. It turns out that they use "aku/kamu" more than Jakarta people do, and it's a normal thing for them. 

日本人の言語交換のパトナーを探しているので、もしよかったら、友達になりませんか？インドネシア語を教えることができます！ :)