I didn't say it should be the main focus. Also, your comment demonstrates my point (thanks for that). It's arrogant, and demonstrates a lack of insight. If they don't, Yo should care. As I mention in another comment below, this impacts their reputation. Imagine if the developers of Yo build something that really should be secure one day. First thing I'd think is they don't bother with security, so I won't use that app. Or the developer interviews somewhere else one day -

Interviewer: "So dude, what have you done in your career?"

Yo dev: "I built Yo."

Interviewer: "Yo got hacked. Goodbye."