Just because you agree to a thing doesn't mean you like it. When enough people have been sufficiently pissed off about an issue, you get demonstrations, riots, and all sorts of mass protests about The State Of That Thing We Don't Want/Like.
I'd really like to see internet protests driving some actual worthwhile changes, not least because on the whole they're a lot less destructive than an actual riot[1]
As developers, instagram can do absolutely anything (legal) they like with their app, and we should totally support them in that.
As a business, they're somewhat beholden to their customers to either do things the customers want (and not hte things the customers don't want), or find a new set of customers.
Otherwise, they stop being a business.
[1] except maybe CloudFlare ends up with a slightly higher bandwidth bill for the DDOS.