For the most part, this appears to strike a healthy balance between convenience and respect: you'll have an easier time watching back-to-back video when you want it, but won't risk blasting others with unwanted audio. With that said, you might not like it so much if this autoplays sound on the next video ad you see. That last part may be another key reason why Instagram is making autoplaying sound a tap-once option. Advertisers frequently want you to listen to their promos, not just look at them, and this increases the chances that you'll hear a catchy jingle or otherwise focus on an ad you'd otherwise skip.