The only time i find it good is for evidence saying you said one thing or another and u have written proof. Iono why i keep all my emails too. My first email from gmail is me thanking my inviter.
I keep all my old pictures back at home on my computer but i keep switching computers and loose track of them but even the ones i have now... i don't look back through them. Its like once in a random blue moon that you MIGHT need it for something.